August 25, 2015 | 13:03 GMT

Aug. 25

The Saudi-led offensive against rebels in Yemen has lost its initial momentum. After breaking out of Aden and advancing into the lightly defended areas of Lahj and Ibb provinces, anti-Houthi advances have now reached areas where forces loyal to former Yemeni President Ali Abdullah Saleh, which include the Houthis, are more concentrated.

In the west, fighting has been focused on the city of Taiz, where the urban terrain and entrenched Houthi positions have slowed the offensive significantly. Houthi forces are, however, reportedly still consistently losing ground. Just as when they began losing control of Aden in July, Houthi forces have started to fire rocket artillery from positions removed from the city, indicating that severe opposition is forcing them to adopt maneuvers to stall approaching forces.

To the east, where anti-Houthi forces have already captured the city of Lawder, Houthi forces have successfully ambushed units in the Mukayras area, preventing northwestern operations into Bayda province. As forces reorganize following the breakout from Aden and as more resources are brought into the area, anti-Houthi forces will eventually be able to overpower Houthi and pro-Saleh forces in Yemen's southern regions. Still, the loyalists' momentum has undeniably faded.

In the north, Saudi Arabia is working to open another front in Marib. There have been reports of coalition forces reinforcing local fighters there, but no significant gains or offensive operations have emerged so far. Reports now indicate, though, that larger formations of armored vehicles arrived in Marib over the weekend, and a decisive offensive push driving west toward Sanaa, the capital, will likely become apparent soon.

Houthi fighters have not sat idly by while losing ground in southern Yemen. Instead, they have increased cross-border operations into Saudi Arabia in retaliation for Saudi operations in Yemen. According to reports, Saudi forces have vacated positions on the border in several areas and are instead simply suppressing Houthi activity with artillery. In most of the mountainous border area, Houthi forces do not present a strategic threat, though they have ambushed several Saudi military units, causing Saudi forces to abandon a substantial amount of equipment.

Meanwhile, a sustained bombing campaign has begun in Aden against the groups that recently regained control over the city – the Southern Resistance and troops loyal to embattled Yemeni President Abd Rabboh Mansour Hadi. There are also reports that al Qaeda in the Arabian Peninsula militants are openly moving through certain areas of the Aden Peninsula. But though the jihadist group has exploited the crisis to establish stronger control over certain locations in Hadramawt province, it is not entirely clear yet whether the fighters seen in Aden are actually members of al Qaeda in the Arabian Peninsula. They could instead be remaining elements of Houthi or pro-Saleh forces that are now conducting subversive actions in the rear of the coalition-supported forces.

Aug. 11

Anti-Houthi forces supported by the Saudi-led coalition have built up significant momentum in Yemen. To the south, Southern Resistance fighters have renewed their efforts after capturing Aden, pushing north and northeast from the port city. Greatly assisted by an influx of combat power, including Saudi-operated armored units, they captured Lahj and al-Anad air base last week and are advancing. The Southern Resistance recently liberated the city of Zinjibar, a major gain that allows them to push farther into Abyan governorate where they intend to link up with friendly forces locked in battle with Houthi- and Saleh-aligned elements near Lawder.

The Houthis, along with forces loyal to former Yemeni President Ali Abdullah Saleh, are in an increasingly precarious position after the liberation of several localities in the Ibb and Dhamar regions. This has led them to dig in and fortify some of their stronger urban positions, namely the cities of Taiz and Ibb. The Southern Resistance has given Houthi defenders in Ibb — 46 kilometers (28 miles) northeast of Taiz — 48 hours to withdraw from the city. Despite their impetus to drive on, rebel forces are reluctant to simply push into population centers, in part because of the risk of inflicting collateral damage and in part because of the perils of clearing well-defended urban terrain. 

Yemen's capital, Sanaa, remains firmly under Houthi and Saleh control for now, but coalition-supported forces have closed to within 100 kilometers (60 miles) of the city. As well as encroaching from Dhamar governorate to the south, coalition-backed Yemeni fighters are massed in Marib, 120 kilometers (75 miles) east of Sanaa, having moved in from Saudi Arabia via the al-Wadiya border crossing earlier this month. Before moving on the capital, coalition-backed forces are likely to neutralize the surrounding area first, defeating Houthi and Saleh elements in the key popular centers of Taiz, Ibb and Dhamar city.

The civilian population in Sanaa is largely anti-Saudi, which could complicate efforts to seize the city. Significant protests are common against the Saudi-supported operation to pacify Yemen and against naval blockades that are preventing an influx of essential goods. A number of tribal groups have sided with the anti-Houthi movement, helping to accelerate the pace of operations in places such as Ibb. This boost and Saudi armored, air and logistic support mean that rapid gains are likely to continue, especially in less urbanized areas. 

Aug. 6

Media reports citing Yemeni military sources indicate that dozens of tanks, armored vehicles and personnel carriers accompanied by hundreds of Saudi-trained Yemeni troops entered Yemen overnight from Saudi Arabia via the al-Wadiya border crossing.

If confirmed, this development is significant. Stratfor has long anticipated a push by coalition ground forces toward Sanaa through Marib. The terrain along this route is favorable, making a push through it more viable than one toward Sanaa south through Sadaa or north from Aden and Lahj. The highway network in Yemen, specifically S150 and N5, permits movement and resupply from Saudi Arabia. The terrain from the al-Wadiya border crossing to Marib also allows armored units room to maneuver — especially with air support.
 
Once coalition forces reach Marib, however, the terrain becomes more challenging. The landscape becomes rugged in the 153-kilometer (95-mile) corridor along highway N5 between Marib and Sanaa. The terrain along highway 515, the equally long southern route from Marib to Sanaa, is even more rugged and restrictive.

By pressing on Sanaa from the east, the coalition would force the Houthis and allied supporters of former President Ali Abdullah Saleh into a two-front war, a position further complicated by the Houthi need to maintain forces in the north to protect the movement's heartland in Sadaa from a Saudi thrust from the north. If the coalition could seize control of the capital, Sanaa, it would be an important symbolic victory. It would also deprive the Houthis of significant resources from taxes and black market fuel sales. Taking Sanaa might also flush Houthi leader Abdul-Malik al-Houthi, former President Ali Abdullah Saleh and other senior opposition leaders out of hiding.

Elsewhere reports have emerged that Yemeni opposition forces launched an attack against Saudi forces in Najran. As coalition and southern resistance forces have pushed rebel forces out of the Aden area, al Qaeda in the Arabian Peninsula has also allegedly seized three new towns near Aden. In Abha, a town in southwest Saudi Arabia close to the Yemeni border, a suicide bomber attacked a Salafist mosque used by a Saudi state security unit known as the Special Emergency Force. The bomber, who was reportedly disguised as a janitor, killed 13 people, including 10 members of the unit.

There has been no confirmed claim of responsibility yet, although a claim purportedly from the Islamic State is circulating on Twitter. The target and location of the attack mean that it could have been the work of either the Houthis or the Islamic State. The Islamic State's Wilayat al-Najd affiliate group has attacked Shiite mosques in Saudi Arabia's Eastern Province in recent months. This was a similar soft target and apparently not as well protected as Shiite mosques, but to date the Islamic State has not attacked Salafist mosques in Saudi Arabia. If it is confirmed that the Islamic State was responsible, it will broaden the scope of the threat it poses to Saudi Arabia.

Aug. 3

A large force of Southern Resistance fighters backed by Saudi-led coalition armored fighting vehicles have reportedly seized control of al-Anad air base, located north of the city of Lahj. The deployment of 3,000 ground troops — 1,500 Saudi and Emirati personnel and 1,500 trained Yemenis — with main battle tanks and infantry fighting vehicles is a notable escalation in the Saudi-led coalition's involvement in Yemen. It is also a sign that Riyadh is willing to take additional casualties.

As the tide of war in Aden began to shift toward the Hadi-aligned Southern Resistance in previous weeks, Riyadh exploited the opportunity to begin moving heavier equipment into the port of Aden. An influx of light armored vehicles greatly assisted the anti-Houthi movement in retaking the city. With the Aden Peninsula coming back under Hadi control, the Saudi-led coalition has deployed significant numbers of men and materiel by ship. The added complexity and logistic burden imposed by forward mounting an armored force left Riyadh with little choice but to deploy its own personnel to use the equipment. This is a significant commitment to the campaign, but a necessary one. To operate a large-scale armored formation requires a high level of training, expertise and support, beyond what the Yemeni resistance forces alone could muster. 

Al-Anad is the first objective for the Saudi-backed fighting force. It is the largest air base in Yemen, and formerly the home of U.S. forces engaged in counterterrorism operations against al Qaeda in the Arabian Peninsula. The United States withdrew its forces from the base in March 2015 when it came under attack from Houthi militants backed by remnants of the Yemeni armed forces loyal to former president Ali Abdullah Saleh. The Houthi thrust was an attempt to dislodge forces in al-Anad that were loyal to Yemen's internationally recognized government, led by President Abd Rabboh Mansour Hadi.

Since then, the base has changed hands several times. It has also been severely damaged during the fighting, and its arms storage facilities have been heavily looted. Situated approximately 48 kilometers (30 miles) north of Aden, al-Anad lies near the southern limit of the Houthis' military expansion and far from the group's northern power base. The facility is also at the confluence of Aden's coastal plain and the southern portion of Yemen's mountainous backbone. The southern approach is favorable terrain for coalition armor. Backed by air power, Saudi tanks and fighting vehicles have ample space to maneuver, creating a problem for the Houthi defenders.

However, the terrain just north of al-Anad tells a different story. It is very mountainous, with limited routes along which armor can move. This will provide Houthi and Saleh-aligned forces with a defensive advantage, more so than they had in Aden or Lahj. The heavily channeled terrain provides ample opportunities for mines and improvised explosive devices and offers positions for anti-armor ambushes. The defenders will also be able to shell the base and its approaches from elevated positions in the mountains. Additionally, the fact that the Saudis have bombed several bridges on important highways — part of the Saudi air campaign meant to cut Houthi supply lines running from the group's stronghold in northern Yemen to the south — will now actually hinder mobility for the coalition forces themselves through the mountain passes.

At this point, the coalition clearly has the upper hand in the area surrounding Aden. They have been able to reopen the port and the airport in Aden, establishing essential air and sea bridges to move personnel, supplies and equipment. The coalition will also likely attempt use al-Anad as a supply hub once the airfield there is secured. Still, their airlift capability is limited compared to what they can bring in via the port. The Saudi-led coalition undoubtedly has superior logistics, firepower and manpower, and has amassed an impressive modern fighting force. However, the farther the coalition moves from this beachhead into the hostile terrain of Yemen's mountains, the more exposed they will be to ambushes and counterattacks. Saudi forces took heavy losses in the 2009 war with Yemen, when Riyadh's offensive operations against the Houthis were staged in the mountains of northern Yemen.

Despite months of fighting against forces loyal to Hadi, the southern movement, and tribal forces backed by al Qaeda in the Arabian Peninsula, the Houthis are still far better armed than they were in 2009, thanks to the vast quantities of military ordnance they successfully looted from government stockpiles over the past year. Dislodging them from their mountain strongholds will be a formidable undertaking, but the coalition forces are beginning to show their commitment. Still, the true motivation behind Riyadh's latest actions in Yemen remains to be seen. It could be either the beginning of a sustained effort to totally defeat the Houthi- and Saleh-aligned forces on the battlefield, or an effort to ratchet up pressure to force a political settlement that would end the conflict. 

Yemeni rebel leader Abdul-Malik al-Houthi said in an Aug. 2 speech that a political settlement with the country’s exiled government was still possible, despite the ouster of the Iran-backed rebels by their Saudi-backed counterparts from the port city of Aden. The Houthis would welcome any mediation effort by a neutral party, whether Arab or international, he said. Meanwhile, the prime minister of Yemen’s exiled government, Khaled Bahah, arrived Aug. 2 in Aden, nearly two weeks after his forces retook the city. 

July 29

A car rigged with explosives detonated outside the al-Fayd al-Hatimi mosque in eastern Sanaa, killing three people. The local Islamic State affiliate, Wilayat Sanaa, claimed responsibility for the attack and said it was retaliation for Ismaili support of the Houth rebels, according to messages posted on Twitter. Meanwhile, the internationally recognized Yemeni government said it will incorporate the anti-Houthi Popular Resistance militiamen into the army.

July 28

A humanitarian truce in Yemen failed to take hold as Saudi-led airstrikes resumed July 28 against Houthi rebels who continued to fight with loyalists. The truce was implemented just a day earlier and was scheduled to last five days to enable aid workers to deliver humanitarian relief to the country. Airstrikes targeted Houthi positions north of Aden, the port city recaptured by anti-Houthi forces last week, and also struck rebel positions in Lahj province. 

July 27

Saudi forces retaliated against Houthi rebel shelling of a border region in Yemen. No additional details were provided about the incident, which comes just hours after another "humanitarian cease-fire" between rebels and Saudi-backed forces in Yemen was scheduled to begin. Additionally, Saudi-led coalition jets mistakenly hit positions held by pro-government forces in Lahj province in southern Yemen

July 26

Yemeni forces allied with the Saudi-led coalition fought Houthi militia for control of the al-Anad air base July 26, local residents said. The fighting for Yemen's largest air base north of Aden comes hours before a five-day cease-fire is supposed to take effect to allow for the delivery of humanitarian aid. But the truce, which the Arab coalition announced July 25, was cast into doubt when Houthi leader Abdul-Malik al-Houthi was reported to have rejected it, arguing it would only benefit the Islamic State and al Qaeda.

July 25

The Saudi-led coalition in Yemen called a five-day humanitarian truce that will begin midnight, the Saudi Press Agency reported. The coalition specified it would respond if Houthi rebels violate the cease-fire.

July 24

Representatives of former Yemeni President Ali Abdullah Saleh have been meeting with diplomats from the United States, the United Arab Emirates and Britain, the leader of Saleh’s Congress party said July 24. The negotiations are taking place in Cairo and are aimed at finding a solution to the conflict in Yemen, he said. An official statement from the Congress party later denied any meetings. Western diplomats contacted by Reuters downplayed the meetings, saying they are part of regular discussions with Yemeni officials.

July 23

Houthi forces fired rockets at Aden's airport July 23, one day after the facility reopened. Three of the rockets landed near the runway, where a Saudi cargo plane carrying 20 tons of humanitarian aid was parked. Aden's airport has been closed for the duration of the four-month conflict in Yemen, but it reopened after Saudi airstrikes helped forces loyal to exiled President Abd Rabboh Mansour Hadi gain control of most of Aden.

July 22

A Saudi military plane landed in the Aden airport, the first since anti-Houthi forces seized the airport from Houthi rebels. Planes carrying unspecified relief supplies are expected to land in the next two days. 

July 21

A car bombing claimed by the Islamic State killed four in rebel-controlled Sanaa. Another eight people, including several children, were wounded in the attack. Sunni extremists have carried out attacks against Shiite targets in Yemen since March. According to unnamed sources, another 11 Houthi fighters were killed in separate attacks overnight.

July 17

After months of intense fighting, the battle for Aden appears to be over. Advancing from the direction of the airport and through the Khormaksar district into the neck of the peninsula, Southern Resistance forces made good use of their new armored capability, liberating the Crater district from the Houthis and capturing key rebel leaders in the process. The Southern Resistance armored thrust then continued through the Maala port district and on to Tawahi. Rather than die in place, many Houthi fighters have surrendered. The isolated pockets of resistance that do remain are in tactically untenable positions and will likely not hold out long. The city of Aden is for all intents and purposes under Southern Resistance control.

Some Houthi forces were able to escape the final push and are headed northeast, where reports suggest they intend to regroup in Abyan governorate. One of the instrumental factors in Aden's fall to the Southern Resistance was the surrender of the 39th Armored Brigade, which was loyal to former Yemeni President Ali Abdullah Saleh. Losing the brigade, stationed at the military base at the airport, was a major blow for the lingering Houthi fighters in Aden. 

Keen to exploit the fledgling victory, Yemeni President Abd Rabboh Mansour Hadi immediately dispatched government and security officials to the city. Hadi seeks to rapidly reestablish as least a perception of political control over the peninsula. However, beyond the current pragmatic cooperation between military forces loyal to Hadi and the Southern Resistance militia, these parties are not politically aligned. Hadi is the internationally recognized president of Yemen but the Southern Resistance is the strongest physical element on the ground. Without a common and present enemy threat to act as a unifier, conflict over the political control of areas liberated from Houthi fighters is a disquieting possibility.

Both sides will attempt to limit such a conflict from emerging until their mutual interest in combating Houthi and Saleh forces results in some kind of resolution. At the same time, the success in Aden gives reason for Hadi and the Southern Resistance to pursue military action over negotiations, mainly because of the prospect of continued military success in the near future.

July 14

The U.N.-brokered cease-fire that was supposed to bring a temporary halt to fighting in Yemen over Ramadan failed before it even started. Supposedly taking effect midnight on July 10, the humanitarian truce was largely ignored by forces on the ground — fighting continued through the weekend. Forces loyal to Yemeni President Abd Rabboh Mansour Hadi claim they were not ordered to commit to the cessation of hostilities, though disrupted communications may have been partially responsible. Rumors suggest that new negotiations are being prepared but only if former Yemeni Prime Minister Khaled Bahah replaces Hadi as president. At the moment this remains an outside possibility. Even with serious negotiations or a more durable cease-fire underway, it is highly likely Yemen will simply move into another phase of conflict rather than achieve a peaceful resolution.

Saudi-led airstrikes against Houthi positions resumed July 13, killing at least 21 civilians and wounding 45 others in Sanaa, witnesses and medics said. Because of the paucity of Houthi targets outside of population centers, Saudi air power has been increasingly striking closer to populated areas, incurring higher levels of collateral damage as a result. Airstrikes also hit the Houthi stronghold of Saada in northern Yemen.

The Battle for Aden

Meanwhile, in Aden, Southern Resistance fighters made significant gains July 14, recapturing the port city's contested airport and an adjacent military base from Houthi rebels. The fighters were aided by Saudi combat aircraft and have continued to push farther south into Aden's Khormaksar district. Houthi opposition to the Southern Resistance is now reportedly weak, with many rebels surrendering or withdrawing from the city. Unconfirmed reports indicate that Republican Guard forces loyal to former President Ali Abdullah Saleh removed their support for the Houthis in Aden, leaving them to deal with the Southern Resistance offensive alone.

A further boon to anti-Houthi forces in Yemen arrived in the form of a large delivery of modern armored vehicles, likely from Saudi Arabia or the United Arab Emirates. These protected mobility vehicles were used extensively in July 14 operations in Aden. In addition to improving the Southern Resistance's overall mobility, the RPG-protected vehicles can deliver personnel close to the fighting and provide intimate fire support from onboard heavy weapons. This improved capability, combined with the weakened position of the remaining Houthis in Aden, has significantly tipped the balance of power in favor of the Southern Resistance. Based on recent developments, the battle for Aden could be in its final stages. Following an anti-Houthi victory in Aden, Southern Resistance forces will likely be redirected toward the battle fronts in Lahj, Taiz and Abyan, where Houthi rebels have also faced severe resistance but have as yet remained unbroken.

July 10

An unnamed Saudi official said that the U.N.-backed humanitarian pause in the conflict in Yemen will be "useless" because Houthi rebels do not have full control of their forces. During a five-day truce in May, the Saudi-led coalition accused the Houthis of violating the terms.

Analysis: Following continued attempts by U.N. representatives to establish a cease-fire during Ramadan, Yemen's belligerents have finally reached an agreement. That the cease-fire is being enacted without a withdrawal of Houthi forces, something previously demanded by the government of President Abd Rabboh Mansour Hadi, indicates the minimal impact this cease-fire will have on a resolution of this conflict in the long term and Hadi's limited ability to force the issue with the Houthis despite the Saudi intervention. Read the full analysis here: Yemen's Cease-Fire Will Not Bring Permanent Peace.

July 9

The United Nations envoy to Yemen, Ismail Ould Cheikh Ahmed, announced a humanitarian pause in the Yemen conflict set to begin July 10. The temporary truce will last through the end of Ramadan on July 17, allowing civilians in the country to receive humanitarian aid. Despite the announcement of the truce, warring factions in Yemen have so far failed to reach a permanent resolution to the conflict. The envoy held talks with officials from both the exiled government and Houthi rebel leaders in Sanaa.

July 7

An estimated 176 fighters and civilians were killed in airstrikes and clashes in Yemen on July 6, local residents and pro-Houthi media said July 7. This would make it the deadliest day in Yemen since the Arab coalition bombing campaign began in late March. Given the unwillingness of any side in the Yemen conflict to accept a compromise in negotiations, fighting continues across the troubled nation.

July 6

Yemen's internationally recognized government has said it expects to reach a deal on a cease-fire soon. Meanwhile, the Yemeni government staged more airstrikes in Sanaa. Thousands have been killed in airstrikes since March, and aid organizations have largely been unable to deliver supplies to the country. U.N.-brokered peace talks have been tumultuous.

July 4

Yemen's Houthi rebels said July 4 that they are in discussions with the United Nations about a humanitarian pause to fighting until the end of the Muslim holy month of Ramadan. The cessation of fighting would allow deliveries of much-needed humanitarian aid in the embattled country. On July 2, the U.S. State Department called for a humanitarian pause to the conflict to allow aid groups to deliver food, fuel and medicine.

June 25

A U.S. drone strike killed four suspected Al-Qaeda in the Arabian Peninsula militants in southeast Yemen. The attack targeted a camp in militant-controlled Mukalla.

June 22

Negotiations between the major belligerents in the Yemen conflict have officially ended in Geneva. Representatives from the government of Yemeni President Abd Rabboh Mansour Hadi, Houthi militias and forces loyal to former President Ali Abdullah Saleh parted ways with little to show for their time. The failure to reach an agreement was expected, given the unwillingness of any side to accept compromise in any form.

As a result, fighting continues throughout Yemen. The overall situation on the ground has continued to shift by small increments, but no significant gains have materialized on either side of the conflict, despite the best efforts of the Saudi-led air campaign, which continues at full strength.

Houthi fighters and former military personnel loyal to Saleh have exerted direct pressure on Saudi Arabia by carrying out cross-border raids, a major concern for Riyadh at a time when it needs to foster public support for military operations in Yemen. Several military positions in the Saudi provinces of Jazan and Najran were targeted over the weekend. In one particular attack near Abu Arradeef in Jazan province, Saleh loyalists managed to take control of a Saudi military base after a sustained bombardment from multiple launch rocket systems.

In Yemen, the Southern Resistance remains effective against Houthi forces in the city of Taiz, though the anti-Houthi group's most notable successes since the end of last week occurred north of Aden. After weeks of consistent but limited gains on the northern outskirts of Aden, Southern Resistance fighters finally reached the suburbs of Lahj, which are still under Houthi control. Lahj is the main Houthi anchor position between the port city of Aden itself and the Southern Resistance-controlled al-Anad air base to the north of it.

With the onset of Ramadan, Southern Resistance fighters revealed their intent to consolidate the liberation of Ad Dali and Aden governorates by the feast of Eid, which occurs at the end of the traditional Muslim period of fasting. Beyond wanting to secure its immediate gains, the Southern Resistance may have a more pressing motive. The group is allegedly receiving more Yemeni personnel with valuable foreign training to assist it in its attempts to recapture Aden. However, claims that the Southern Resistance is facing difficulties in paying its fighters casts some doubt over its ability to maintain its offensive operations. 

June 20

A vehicle bomb detonated at Sanaa's Qubbat al-Mahdi mosque in the Old Town area of the city June 20, killing three and injuring an unspecified number of others. Islamic State bombed Houthi rebel political headquarters and two mosques June 17. Peace talks between the Houthis and representatives of President Abd Rabboh Mansour Hadi ended without a deal June 19.

Analysis: The Islamic State launched multiple suicide bombings in Sanaa aimed at Houthi rebels' political headquarters and two mosques June 17, the eve of Ramadan. According to the Yemeni Health Ministry, the attacks killed at least four people and wounded at least 50 more.

It was the Islamic State's fourth attack against mosques in Sanaa. The first and most deadly occurred March 20, when suicide bombers killed over 140 people in the bombing of two mosques during midday Friday prayers. Because al Qaeda has eschewed assaults on places of worship, the attack was unexpected and Islamic State suicide bombers were able to easily sneak into the mosques. Read the full analysis: The Islamic State's Pretense of Strength in Yemen.

June 18

A fistfight erupted on the sidelines of U.N.-mediated peace talks between Yemen's warring factions in Geneva. Yemeni opponents of the Houthi rebels that drove the government out of Sanaa interrupted a news conference held by Houthi officials, throwing shoes and shouting insults at them. Fights then broke out between Houthis and protesters, who were escorted out. Participants in the negotiations, scheduled to wrap up either June 19 or June 20, have reported little progress in the talks. Hamza al-Houthi, head of the Houthi delegation, stayed composed during the confusion.

June 12

In the battle for Yemen, forces opposed to the Houthi rebels appear to have the upper hand, at least for now. Indeed, over the past week, anti-Houthi fighters have made consistent, albeit limited, territorial gains against the rebels and against forces loyal to former President Ali Abdullah Saleh.

In Aden, anti-Houthi forces expanded their territory in the northern and western outskirts of the city. Meanwhile, they have taken ground in the fight near the airport in Aden. In Dali province, the general appointed by President Abd Rabboh Mansour Hadi to lead the contingent of the 33rd Brigade that is still loyal to the government (most of it is not) has refilled his ranks by gathering former military officers. He has also recruited Southern Resistance fighters, who also oppose the Houthis and who have claimed some recent success of their own in Dali. Elsewhere, the counteroffensive against the Houthis in Marib city has proved effective, and the rebels' attempts to enter the city appear unrealistic.

All these gains were made in no small part because of the Saudi-led air campaign, which has degraded the capabilities of the Houthis and Saleh loyalists. But that air campaign is becoming more controversial as it causes more collateral damage. In fact, the campaign came under fire after it destroyed parts of the old city in the center of Aden — a protected World Heritage site. Meanwhile, Saudi Arabia has been unable to quell Houthi activity along its border with Yemen — attacks against military outposts and shelling into Saudi territory continue unabated.

Delegations from the different sides of the conflict have arrived in Geneva to discuss the conflict. The official talks begin June 14, but preliminary talks involving a smaller number of delegates will begin June 12. But because the Hadi delegation continues to insist on a Security Council resolution — something that would require the unconditional disarmament and withdrawal of Houthi forces — the talks will probably not bear much fruit.

June 2

The tide of battle in Yemen appears to be turning in favor of the anti-Houthi movement. After a long period of stagnation, Houthi elements and supporters of former Yemeni President Ali Abdullah Saleh are being gradually pushed back from a number of active frontlines. Though gains are taking time to materialize, progress is being made in places such as Marib, Taiz and Dali. Anti-Houthi forces pushed beyond the city limits of Dali proper, advancing in the direction of Ibb. This is problematic for Saleh, who was compelled to move fighters from Ibb to the city of Taiz, which remains split between Houthi forces and those opposing them.

The alleged success of anti-Houthi forces in Marib is notable because the Houthis had claimed to be diverting efforts to the eastern fronts, following offers of support from sympathetic tribesmen and after becoming gridlocked in the south. In Aden, Houthi offensives have been continually blunted against the opposition, which managed to recapture terrain on the outskirts of the city. In the Aden peninsula, centralized Houthi forces are maintaining their blockade on anti-Houthi fighters located in the Western point of the peninsula, allegedly by using artillery fire to turn away ships laden with much-needed supplies. Meanwhile, Saudi-led coalition aircraft have continued to pound Houthi positions from the air, focusing heavily on the vulnerable border areas.

On the diplomatic front, a new date for the planned Geneva talks was established June 1. Rather than negotiating a new political settlement, however, the Geneva talks scheduled for June 10-14 are being framed as an opportunity to discuss the implementation of an existing U.N. Security Council ruling. It is believed that 14 delegates from the various sides of the conflict will be present. Unlike previous negotiations, which ended up being postponed, ousted Yemeni President Abd Rabboh Mansour Hadi and his Cabinet have already said they are ready to support the talks.

May 11

A humanitarian cease-fire began at midnight in Yemen, initially for five days but with the option of being extended. The call for a cessation of hostilities is the result of a confluence of factors that could edge the Saudi-supported anti-Houthi movement and the Houthis toward the negotiation table. Leading up to the cease-fire, the Saudi-led air campaign has maintained its punishing intensity, but it has not been able to overcome the gridlock on the ground. Riyadh also deployed additional ground forces to the border town of Najran to protect against Houthi cross-border incursions in the wake of last week's indirect fire attacks.

The air campaign has not been without its hazards. A Moroccan F-16 Fighting Falcon flying as part of the Saudi-led coalition crashed over Yemen on May 11. Initial reports said contact with the aircraft was lost after an unknown projectile hit it. Houthi fighters claimed to have shot it down, but there has been no confirmation of the exact cause of the crash. Imagery from the crash site shows no clear marks from enemy ground fire. On closer examination, however, the nature of the debris field indicates that the aircraft broke up in flight before plummeting to the ground. The Moroccan pilot failed to eject before the crash and recent pictures show his body among the wreckage. It is only the second documented case of a coalition aircraft crashing during Saudi-led air operations.

The first incident involved a Saudi F-15 that went down over the Red Sea in March, requiring the deployment of a U.S. Navy search and rescue helicopter to recover the two pilots. Losses are to be expected in this type of conflict, especially with the high tempo of sorties the Saudi-led coalition is maintaining.

The Battle for Aden

In Aden, Houthi forces made gains throughout the peninsula, despite being mostly dislocated from their immediate supply lines. As well as pushing deeper into Tawahi, the Houthis took full control of the Crater district. Just north of the Aden Peninsula, anti-Houthi forces seized control of the Dar Saad district, which further improves their position as well as their ability to lock Houthi and Saleh-aligned forces in the isolated peninsula. Intense fighting continues in and around Aden airport and it is unclear which side holds the terminal. Because of its location at the natural choke point before the peninsula widens, the airport is key terrain. Holding it enables the Southern Resistance fighters to isolate all the Houthi and Saleh fighters deeper in the peninsula, regardless of the territorial gains made in the Tawahi and Crater districts. 

May 9 - Saudis and Houthis Reach a Decision Point in Yemen

Following several days of attacks by Houthi forces on towns just across the Saudi border, Riyadh has offered Yemen's Houthi fighters a humanitarian cease-fire. At the same time, rumors of a potential limited ground incursion into Yemen are growing louder. The Houthis have forced the Saudis to make a decision. With the option of either sitting down at the negotiating table under a cease-fire or being drawn into a ground incursion inside Yemen, Riyadh will have to carefully evaluate its strength and the risks involved in either situation.

While military operations in Yemen have significantly constrained the movement of the Houthis and their allies; the air campaign has not yet been able to reverse their earlier gains; and the threat along the Saudi border has not been eliminated. A humanitarian cease-fire lasting at least five days, allegedly to begin on May 12, leading to a negotiated settlement would offer Saudi military decision-makers both short-term results and a more sustainable long-term stability.

April 30-May 5

Ground fighting continues in Taiz, Lawder, Lahj, Dali and Marib between Houthis and elements aligned with former Yemeni President Ali Abdullah Saleh on the one hand and anti-Houthi forces on the other. Although no significant gains have been made by either side, the Saudi-led air campaign has limited the ability of the Houthis to project power across the country.

The battle for Aden is ongoing, with the heaviest fighting focused near the airport, which anti-Houthi fighters allegedly still control. Coalition aircraft have been pounding Aden heavily, dropping ordnance on Houthi and Saleh positions in the Maala port district, around the airport and in the northern Dar Saad district of the city. Over the weekend, anti-Houthi fighters in Aden received a much-needed uplift in manpower. If observers on the ground were correct, these reinforcements reportedly came from the United Arab Emirates and are soldiers of Yemeni descent. The new troops were involved in fighting adjacent to the airport, likely in an attempt to exploit the recent gains made by the Southern Movement militia.

Although there is no hard evidence that Saudi or UAE special operations forces are accompanying the new fighters, it is probable that coalition specialists are present in Aden in some form, helping organize anti-Houthi forces as well as coordinating air assets. The deployment of reinforcements to Aden illustrates the Saudi intent to directly influence ground operations. The air campaign is doing a good job of interdicting the movement of Houthi and Saleh forces, and increased cooperation between local resistance groups and periodic uplifts in combatants will be instrumental in staging further counteroffensives. Houthi forces have made some gains, however, mainly around the port district, but the loss of the airport imposes a huge barrier to their attempts to take control of Aden.

On Yemen's northern border, Houthi fighters conducted several more incursions into Saudi Arabia. Saudi forces have allegedly been forced to abandon several border posts, and in the city of Najran, flights to the airport were suspended and schools closed because of shelling by Houthi mortars and rocket artillery. These incursions into Saudi Arabia by the Houthis are not isolated, but it is the first time a population center has been directly targeted. Riyadh will continue to have problems closing down its porous border with Yemen, but Houthi fighters are likely to remain a threat only in the immediate vicinity of the border, lacking the ability to conduct deep cross-border operations. 

April 29

The battle for Aden is becoming increasingly desperate for the remaining Houthi and Saleh-aligned forces on the peninsula. In a bold move, opposition fighters from the ardently anti-Houthi Youth Resistance made a significant push from the Mansoura district of Aden toward the airport. Houthi and Saleh fighters are now completely cut off from their supply lines, though they still control the Badr Air Force Camp south of the airport, along with the control tower and surrounding buildings. Despite losing ground to the north, however, the Houthis were able to recover territory along the eastern coastline of the Aden Peninsula, including the disputed seaport. They were also able to take and hold the Russian consulate, a key defensive node.

Buoyed by success, the Youth Resistance is calling for all able-bodied fighters to flock to the front line. Because of the rapid gains made against them, Houthi and Saleh forces in Aden city have now become trapped between the Khormaksar, Maala and Crater districts. It is a position that will be difficult to maintain, so long as they are wedged between the offensive coming from the north, and the anti-Houthi contingent in the Tawahi and Crater districts that continue to hold their ground. If the Houthis are unable to receive supplies or reinforcements soon, the battle for Aden may well be in its final stages. The sustained interdiction of Houthi supplies and reinforcements, resulting from previous successful offensives near Lawder, Lahj and Taiz, has given the anti-Houthi forces a tactical advantage on the ground.

Elsewhere in Yemen

Fighting in Taiz governorate continues, though interruptions have periodically occurred as a result of local humanitarian cease-fires. The Saudi-led coalition parachute-dropped supplies and weapons to resistance fighters opposing Houthi and Saleh-aligned forces in and around Taiz city.

In Abyan governorate, anti-Houthi forces continue to make substantial gains near Lawder. The coalition air campaign is showing no signs of abating, causing attrition to Houthi and Saleh targets around Sanaa, as well as in Marib, Aden and other locations around Yemen.

April 24-28

Despite the transition from Operation Decisive Storm to Operation Restoring Hope, Saudi-led coalition airstrikes continue with no reduction in intensity, targeting Houthi and Saleh-aligned forces across Yemen.

Fighting endures in Taiz and Lahj governorates as well as along other main supply routes and logistic corridors. In the ongoing battle near Lawder, abutting the northeastern Houthi supply lines into Aden, Southern Movement fighters have been making significant gains. They have established control over key locations and severely damaged a Houthi convoy attempting to move through the area.

By blocking essential supplies, the fight for Aden has turned into a mutual starvation war of sorts. Houthi and Saleh forces inside Aden are isolating pro-Hadi and other anti-Houthi fighters in several districts at the bottom of the peninsula, while Southern Movement fighters that have fought their way into Aden from the north are isolating those Houthi and Saleh forces by complicating their resupply and reinforcements. The Houthi and Saleh forces have in turn taken control of the banking sectors in the governorates surrounding Aden and are preventing the local population from accessing essential funds and salaries.

Inside the city of Aden itself, Houthi and Saleh forces have been trying to hit back against the Southern Movement offensive from the north, which occurred last week. They have taken positions at the University of Aden and the hospital (both in Khormaksar district) and have been engaged in heavy fighting with Southern Movement fighters there. Coalition aircraft and ships also continue to strike Houthi and Saleh positions in Aden.

Just north of the Aden Peninsula, Houthi forces have pushed west, trying to recover key terrain they lost earlier to local militias, exposing them to the risk of being cut off from their supply lines from the north.

In an effort to prevent aid getting through to Houthi and Saleh elements elsewhere in Aden, Saudi aircraft bombed Sanaa International Airport, preventing an Iranian cargo aircraft from touching down. It was believed that the aircraft contained aid for the Houthis, but could also have contained weapons or military equipment. Sanaa airport remains closed to air traffic. Bombing the runway was a creative solution to preventing Iran from landing supplies — without shooting down the plane — but it also means than any other humanitarian flights will no longer be able to use the airport as long as it is closed, or Saudis prevent aircraft from landing.

A Saudi military spokesman said the Iranian aircraft did not coordinate with coalition authorities and the pilot ignored a warning advising him to turn back. The denial of supplies fits into the larger picture of preventing Iranian-facilitated logistic support from reaching Houthi and Saleh fighters. A convoy of Iranian cargo ships, allegedly carrying weapons, was diverted April 23, following multiple statements saying that they would not be allowed to dock in Yemen. The United States even diverted an aircraft carrier from the Persian Gulf to track the convoy. As well as Saudi and Egyptian vessels, there is a sizable U.S. Navy presence in the Gulf of Aden. 

April 23

A shift occurred in the Saudi-led military campaign in Yemen; interpreted by some as a cessation of hostilities, or an end to the Saudi-led air campaign. In reality the change is much more nuanced and indicative of Riyadh's broader strategy. The interplay of consecutive operations in a military campaign and the efforts to achieve a negotiated solution to the crisis are driving a change in focus, not an actual end to military operations.

April 21-22

Iran dispatched a naval convoy of freighters to international waters near the border of Oman and Yemen, raising new fears of a potential confrontation in the region. The convoy, last reported to be stationary, is assumed to be a possible attempt to support Houthi fighters and forces loyal to former Yemeni President Ali Abdullah Saleh. It comes in spite of a blockade implemented by Saudi, Egyptian and UAE ships. U.S. officials, as well as the Saudi-led coalition, suspect that the convoy contains arms. Consequently, the United States has rushed an aircraft carrier and a guided missile cruiser to the area. Overall, Iran has a weak military hand to play in Yemen. Deploying the convoy there may be more about shaping a political narrative than achieving a military objective on the ground.

Read the full analysis: Iranian Naval Presence Raises the Odds of Confrontation

April 17-20

In an effort to support the offensive to capture Aden, Houthi militias and forces loyal to former Yemeni President Ali Abdullah Saleh have fought hard to maintain supply lines to the southern port. This has been no easy task, with the opposition continually interdicting and harassing vulnerable logistic chains. Over the weekend, the anti-Houthi Southern Movement succeeded in isolating Houthi and Saleh-aligned forces in Aden, making a push to the west of the city and taking ground adjacent to the Imran port area, cutting off several supply routes.

Not only does this — combined with the other operations in Lahj and Lawder — leave Houthi and Saleh forces stranded in Aden with finite supplies of ammunition and fighters, but it also cuts off their withdrawal route. Further compounding the Houthi position, Southern Movement fighters located at Lahj and al-Anad air base made a bold push south, handrailing the eastern coastline of the peninsula. Maintaining their momentum, they succeeded in taking control of Aden International Airport and the Russian Consulate, effectively insinuating themselves in the Houthi rear. The Houthis and Saleh-aligned forces remaining in Aden attempted to retake the ground lost over the weekend but with no success. Reports indicate the Southern Movement militia consolidated in the Russian Consulate and is continuing to push further south.

Though fighting continues along static lines in the Maala and Crater districts of Aden, the opening up of a second front is a serious diversion for Houthi and Saleh fighters. Committed in both directions, facing an aggressive enemy with ready access to fresh manpower and supplies, the Houthis run a considerable risk of becoming fully encircled in the geographically isolated Aden Peninsula. If the Southern Movement continues to push home its advantage, the battle for Aden could take a rapid turn in favor of the anti-Houthi militias.

A victory in Aden would not only boost morale among the populist militias, but it would also provide a staging post from where the anti-Houthi Southern Movement, backed by several military units still loyal to beleaguered President Abd Rabboh Mansour Hadi, could expand. Previously committed forces would be freed up to reorient toward Lahj, Lawder and potentially further afield in places such as Taiz province, where anti-Houthi forces have already made gains. By focusing outward, the Southern Movement can open up new offensives, support existing ones, or expand captured areas. Besides securing the fallback refuge of Hadi — currently residing in Riyadh — holding Aden provides the anti-Houthi forces with a bridgehead that could be used to receive supplies or even reinforcements from the Saudi-led coalition.

Outside of Aden

In another turn of events, the U.S. Navy carrier USS Theodore Roosevelt is steaming toward the coast of Yemen, reportedly to assist in the operation to interdict Iranian supply shipments to the Houthis. The carrier, which replaced the USS Carl Vinson on April 17, was intended to support coalition operations against the Islamic State in Syria and Iraq. The very fact that the carrier is being reassigned is a good indication of Washington's priorities in the Persian Gulf. The USS Theodore Roosevelt will join the amphibious readiness group already operating off Yemen's coast, led by the USS Iwo Jima.

Also of note, a huge explosion occurred in the Fajj Attan hill district of Sanaa on April 20, following a Saudi airstrike on a Republican Guard military base. The detonation was reportedly so large that blast damage was recorded well over a kilometer away. Scores of buildings were severely damaged, and a Yemeni official from the Health Ministry reported 25 fatalities and over 350 wounded as a result of the explosion, many injured by falling glass. Several foreign embassies were also damaged.

The Republican Guard base was occupied by troops loyal to Saleh and had been hit repeatedly following the commencement of Saudi coalition airstrikes. It appears that the target of the April 20 airstrike was a Scud missile storage depot. Examining footage of the strike, it appears that the outsize explosion may have resulted from a direct hit on the fuel storage facilities. Scuds are liquid-fueled missiles, and the fireball and black smoke immediately after detonation are consistent with petroleum tanks igniting. It is not known how many Republican Guard personnel were killed, but gauging from the number of civilian casualties, the death toll inside the base must have been heavy. If usable Scud warheads remain at the Fajj Attan location, the base will likely receive further airstrikes. At present the location of Saleh is unknown, but the assumption is that he is orchestrating his forces from a well-defended bunker. 

April 14-16

The Saudi-led air campaign is continuing at a high tempo, but the target set is shifting from high-grade targets to objectives with a lower payoff. This is partially thanks to the successful targeting of large-scale weapons depots and specific materiel. With the majority of high-value targets engaged, bombs are starting to fall on opportunity targets. The airstrikes are also becoming more discriminating through necessity; with their mobility reduced, Houthi rebels and forces loyal to former President Ali Abdullah Saleh are embedding themselves in population centers. The Houthis are also exploiting Yemen's difficult mountain terrain to avoid airstrikes. The constant threat of close air support — and its particular effectiveness on ground columns, massed vehicles and personnel — has slowed Houthi ground offensives on the whole, while keeping anti-Houthi forces in the game. 

As an additional boost to the forces opposing the Houthi and Saleh onslaught, large numbers of previously neutral military units have, in the past few days, confirmed their allegiance to embattled President Abd Rabboh Mansour Hadi. The perceived success of the air campaign, coupled with the fact that to do nothing is to eventually become a target, either from the air or on the ground, are likely explanations. Notably, even a number of previously pro-Saleh units have come out in recognition of Hadi's right to rule, pledging their allegiance in the process.

Capitalizing on Chaos

Taking advantage of the tumultuous situation in Yemen, al Qaeda in the Arabian Peninsula has been pressing its advantage, consolidating control in the coastal region of Mukalla. Al Qaeda fighters successfully took control of the Mukalla seaport, Riyan air base and the al-Dhaba oil export terminal on April 16. Riyan air base was home to both the 27th Infantry Brigade and the 190th Air Defense Brigade, both loyal to Hadi. The brigades initially refused to hand control of the facility to al Qaeda in the Arabian Peninsula, but after brief clashes the military units withdrew. Not only does al Qaeda control the air base, it allegedly has access to the remaining air defense equipment not removed or disabled.

The two military groups were in a difficult position to begin with. By opposing the Houthi and Saleh militias, the pro-Hadi forces found themselves inadvertently aligned with al Qaeda in the Arabian Peninsula, which is vehemently anti-Houthi and supports combat operations against them. This tension was likely a driving factor in the withdrawal of the military; an engagement with al Qaeda would have been detrimental to both, diluting combat power at a time when the Houthis present the biggest threat. 

To some extent, al Qaeda in the Arabian Peninsula already controlled Mukalla, Riyan, Ghayl Ba Wazir and Ash Shihr. The significance of the group's April 16 move is in the consolidation of control over the area, as a result of taking direct ownership of critical infrastructure. Al Qaeda in the Arabian Peninsula is actively blunting the Houthi offensives. A good example of this is the sustained vehicle-borne improvised explosive device campaign against Houthis in the Lawder area over recent days. Despite its anti-Houthi stance, al Qaeda in the Arabian Peninsula is gladly using the situation in Yemen to expand its actual control in different parts of country, where no one is capable or willing to oppose it.

Yemen's Contested Battlespace

The situation in the southern port city of Aden remains largely the same. Houthi and anti-Houthi forces continue to fight for key terrain, though the Houthis have the advantage of holding the high ground, occupying positions in the mountains around Aden as well as the Crater district. They are using these elevated fire positions to good effect, engaging the anti-Houthi forces in the city with sniper and harassing fire. Nevertheless, anti-Houthi fighters managed to clear some of the Houthi positions on the Crater slopes, but the high ground is heavily contested.

Northwest of Aden, the battle for Taiz continues in the mountainous province. The pro-Hadi 35th Armored Brigade narrowly escaped encirclement by Saleh loyalists, mainly thanks to the efforts of rural militias. These militias are fighting in support of the 35th in opposition to Houthi and pro-Saleh forces.

The offensive by Saleh forces in Dali, 100 kilometers (60 miles) north of Aden, has effectively been halted. The fighting has further diminished the pro-Saleh 33rd Armored Brigade, which was already depleted by Saudi airstrikes earlier in the campaign.

Near the city of Marib, 120 kilometers east of Sanaa, the Houthis continue to push from the west. The fighting has yet to reach the city, however, because tribal militias are throwing everything against the Houthis in an effort to stop their advance, sustaining heavy casualties in the process. Given the intensity of the close combat, it is uncertain how long the militias will be able to hold out.

April 11-13

The conflict in Yemen shows no sign of abating. Intense fighting continued throughout the weekend, and now, a number of distinct battlefronts have emerged. Houthi militants and forces aligned with Yemen's former president, Ali Abdullah Saleh, are fighting for control of a number of key localities in the south of the country. At the same time, they are expanding east into Yemen's oil-rich territories, which brings Houthi and Saleh forces into direct conflict with al Qaeda in the Arabian Peninsula as well as other opposing forces.

In the mountainous province of Taiz, the 35th Armored Brigade, a unit that swore loyalty to Yemen's incumbent president Abd Rabboh Mansour Hadi, is assaulting the 22nd Armored Brigade, which is loyal to Saleh. The pro-Hadi formation is greatly supported by Saudi-led coalition airstrikes, and heavy fighting is taking place across the undulating, close terrain of Taiz. In Ad Dali province, tribal fighters are heavily engaging Houthi militias in the town of the same name, and reports from the ground indicate that the tribes are inflicting significant casualties on their opponents. Elements of the Saleh-aligned 33rd Armored Brigade have repositioned to assist, having suffered heavy attrition from the Saudi air campaign in Bayhan district.

Houthi and Saleh reinforcements from Ibb are moving through Taiz toward Aden, potentially to fight anti-Houthi forces around Lahj and al-Anad air base on the way to the port city. The anti-Houthi forces have successfully interdicted Houthi supply lines to the south and have isolated the remaining Houthi and Saleh forces in Aden, severely threatening the offensive. Despite this, the fight for Aden's port remains fierce, particularly around the Hadjiv traffic circle. The Saudi-led air campaign, supported by naval artillery fire, continues to strike Houthi and Saleh positions throughout the city, including the presidential palace. Immediately northwest of Aden, in Sheikh Othman, anti-Houthi militias and forces loyal to Hadi continue to attack.

Aside from the fight for control over Aden, separate offensives are ongoing in the east of the country, where the al Qaeda in the Arabian Peninsula heartland and Yemen's main oil infrastructure are located. Remaining military units have been preparing themselves to face the Houthi advance, including the 2nd Naval Infantry Brigade following its declaration of loyalty to Hadi. The brigade is cooperating with local tribes to set up the defense of the town of Belhaf and its liquefied natural gas facility operated by Total. In addition, local tribes in Hadramawt province have stated their intention to raise an army of 20,000 fighters to oppose the Houthi movement. So far, the Houthis have been able to make significant advances in the east. They captured the capital of the Shabwa governorate, Ataq, last week and are beginning to push into the town of Marib. The Saudi-led coalition has targeted them at both locations to disrupt their advance.

Finally, to the north, the Houthis conducted another border incursion into Saudi Arabia over the weekend. The move comes at a time when Riyadh is actively trying to clear civilians from villages along its southern border. Conventional Saudi ground forces have yet to penetrate south, but Egypt reportedly deployed troops to Perim, and island in the Bab el-Mandeb strait, to conduct a battle damage assessment following airstrikes against Houthi forces. 

April 9-10

Fighting across the Aden Peninsula has stagnated in recent days but remains focused on the Maala and Crater districts. Reports indicate that the tide is turning against Houthi militants and forces loyal to Yemen's former president, Ali Abdullah Saleh. In Sheikh Uthman, a satellite city that is effectively a northern suburb of Aden, anti-Houthi forces and elements of a brigade still loyal to Yemeni President Abd Rabboh Mansour Hadi are threatening to cut off opposing forces inside Aden.

Elsewhere in Yemen, anti-Houthi forces continue to disrupt the supply lines of Houthi and pro-Saleh militias north of Aden. By holding al-Anad air base and interdicting the flow of arms and personnel in Lawder province, anti-Houthi forces have impacted the success of the offensive against Aden.

In Shabwah province, however, the Houthi offensive is proceeding largely as planned, with the town of Ataq falling to the militants. Although resistance was reportedly scant, the success of the offensive was in no small part thanks to the presence of the 21st Mechanized Infantry Brigade, a formation based in the area that aligned with the Houthi and Saleh movement when Ataq came under pressure.

Al Qaeda in the Arabia Peninsula has already begun a guerrilla campaign against Houthi and Saleh forces near Ataq, using at least one vehicle-borne improvised explosive device in what is likely to be a campaign of continued resistance. In Ibb province, located halfway between Sanaa and Aden, al Qaeda fighters have been taking over positions previously abandoned by Houthi forces. 

April 7-8

Heavy fighting continues to define the battle for Aden. Coalition airstrikes and naval gunfire from Saudi and Egyptian vessels have persistently engaged Houthi and Saleh-held areas of the city. The frontline has not shifted significantly and fighting remains focused predominantly on the edges of the Maala port locality and the Crater district. In a blow to the Houthi and Saleh-aligned forces in Aden, however, essential supply lines linking the city with other concentrations of fighters and resources have been effectively severed.

Further north, anti-Houthi militias are fighting to keep control of the al-Anad air base (which they captured April 6), heavily buoyed by Saudi close air support. Besides attempting to take the air base back, the Houthis are trying to re-establish control of the road linking Aden to Taiz, but so far they have not been able to do so. To the east, units of the 111th Infantry Brigade, which remains loyal to President Abd Rabboh Mansour Hadi and was originally stationed in Ahwar, are closing down the town of Lawder, blocking nearby roads. Troops from the Saleh-aligned 15th and 117th infantry brigades are fighting resistance battles around Lawder district itself, attempting to reconnect with Houthi and Saleh forces in Aden.

While the Saleh-aligned units in Lawder are reportedly still receiving supplies from Bayda to the northwest, if Houthi forces and their affiliates in Aden are separated from their supply lines for an extended period of time, it could damage their ability to continue the Aden offensive. Being logistically isolated will also dampen their resistance to smaller counteroffensives by tribal militias and al Qaeda in the Arabian Peninsula fighters in other locations across what is an increasingly disconnected pocket.

Elsewhere, however, Houthi forces continue to advance where they can. They are moving on the town of Ataq, capital of the Shabwa region, and could push even further east into the areas of Yemen where critical energy facilities are located. The presence of al Qaeda in the Arabian Peninsula in these locations could yet slow this advance, however.

Al Qaeda in the Arabian Peninsula is exploiting the divisions within Yemen for its own ends, extending its reach across the country. Most recently, the terrorist organization took control of a border post near Manwakh, on the Saudi border. The group has also been active near Lawder, but rather than showing loyalty to forces aligned with Yemen's erstwhile president, their main interest is in combating Houthi influence in the region. This has resulted in al Qaeda in the Arabian Peninsula coming into conflict with local anti-Houthi militias, and at Mukalla, tribal fighters are still attempting to mount an offensive to push al Qaeda out of the area. 

April 4-6

Over the weekend, Houthi and Saleh-aligned forces recovered ground they were forced to abandon April 3 under pressure from Saudi-led coalition airstrikes. Aside from retaking the presidential palace in the southeast corner of the peninsula, militants also occupied positions on Mount Shamsan overlooking Aden's Crater district, an area that remains strongly contested. On the northern edge of the Aden peninsula, Houthi fighters are pushing hard into the Maala district, where the seaport is located. Although the strategic port remains disputed for now, the security situation is rapidly deteriorating.

On April 4, gunfire from the shore forced a pair of rigid inflatable boats operated by the French navy to turn away from their approach. The French government was attempting the evacuation of 44 civilians of various nationalities from Aden but was forced to enlist the help of the self-proclaimed Yemeni coast guard to shuttle the civilians to ships waiting in open water. Successful evacuation attempts had been carried out days earlier, but as the French effort on April 4 proved, negotiating the port is increasingly treacherous. This creates a problem for fighters opposing the Houthi and pro-Saleh forces in Aden because resupply by sea is now increasingly difficult. Although some supplies were delivered by guided parachute last week, urban fighting is notoriously ammunition-intensive.

Besides placing a burden on logistics and making the extraction of personnel increasingly hazardous, a contested port means that there is now an increased risk to any forces seeking to dock and disembark troops to help secure the peninsula. Though the Houthis and Saleh-aligned militants have made gains, including taking control of al-Ummal island, the forces opposing them continue to put up strong resistance, backed by close air support and supply drops from the air. So far, they have not suffered a defeat that they cannot recover from.

Wider Yemen

To the north of Aden, tribal militias opposing Houthi fighters are staging a number of different offensives. At least some of the tribal thrusts appear designed to cut off the Houthi and pro-Saleh fighters attacking Aden, isolating them from their main body. Near Lawder, the 15th and 117th infantry brigades, loyal to Saleh, are at risk of being cut off. Another offensive near the al-Anad air base north of Aden — now under control of local militias opposing Houthi fighters — could conceivably sever the Taiz to Lahj axis, which the Houthis use as a main supply route. A major bridge along this mobility corridor was destroyed April 6, further hampering the ability of the attackers to bring up supplies and reinforcements. 

Simultaneously, tribal offensives in and around the Marib region have begun against the remains of the Saleh-affiliated 33rd Armored Brigade, which was heavily deteriorated by airstrikes. Elsewhere, tribal militias reportedly mounted attempts to capture the port city of Mukalla, Hadramawt region, from al Qaeda in the Arabian Peninsula. The Saudi-led coalition has been focused on reducing Houthi and pro-Saleh combat power on the ground. In addition to concentrating on the cities of Aden and Sanaa, airstrikes have attacked Houthi positions on Perim island in the Bab el-Mandeb strait as well as near the Saudi border, where ordnance was dropped on manned trench systems south of Najran. Although the opposition forces have mainly consisted of anti-Houthi militias and tribal fighters, Saudi special operations forces have reportedly been active in the conflict. Such forces would likely be operating in an advisory capacity as well as guiding in close air support.

April 3

Continued airstrikes by the Saudi-led coalition have forced Houthi and Saleh-aligned forces to withdraw from their front lines in the southern port city of Aden. Having occupied the presidential palace earlier in the week, Houthi militants were forced to give up their positions in the face of persistent bombing from the air. Falling back from the Shira and Crater neighborhoods and harried by pro-Hadi fighters opposing them on the ground, the Houthi and Saleh militants are now consolidated in the Khormaksar neighborhood.

Several airdrops of weaponry and medical supplies have bolstered the forces loyal to ousted Yemeni President Abd Rabboh Mansour Hadi. The airdrops came down in the Tawahi districts of Aden, delivered by guided high-altitude parachutes, directed by an integral global positioning system. This advanced technology is almost exclusively used by the United States, though the United Arab Emirates has submitted contracts to procure it in the past. It remains unknown whether Riyadh has access to the technology, but Washington previously offered logistical support to the ongoing campaign in Yemen. Among the weapons delivered were small arms, anti-tank weapons, telecommunications equipment and medical supplies.

April 2

Houthi-aligned forces made significant gains in the Yemeni port city of Aden on April 2. Saudi airstrikes had slowed their advance into the central Khormaksar area, but by the end of the day, the Houthi militants and forces loyal to former President Ali Abdullah Saleh were able to establish control over central Aden and the presidential palace.

The rebel gains mean the window of opportunity for a Saudi-led ground operation may be closing rapidly. Forces loyal to embattled President Abd Rabboh Mansour Hadi and militias that oppose the Houthis control only the western portion of the Aden Peninsula, and Houthi mortar shelling is targeting the port now. These developments significantly increase the amount of effort required to deploy forces to the city — and it increases the risk they will incur once there. Such an operation would no longer be a defensive one, but would instead require an offensive action to liberate substantial portions of Aden.

If Saudi Arabia intends to block the rebel forces from taking Aden, it appears it will not be able to mount a response to the rapidly evolving situation on the ground in time. However, Riyadh could still launch such a blocking action, and continued Saudi airstrikes and bombardments by coalition warships indicate attempts to influence the tactical situation on the ground may continue. Stratfor sources also say that Saudi Arabia and Egypt continue to position forces that could deploy to Aden. 

While the city is a strategic port in Yemen, the Houthis will be able to make little use of the harbor and the airfield because of the Saudi-led coalition's naval blockade and no-fly zone. However, the advance does eliminate a core pocket of pro-Hadi forces while destroying the symbolic value of Aden as the last resort of non-Houthi Yemen.

From Saudi Arabia's perspective, however, losing parts of Aden is not catastrophic. Military operations in Yemen have focused on forcing the Houthis to the negotiating table for discussions on returning to the status quo. To do this, Houthi military power — and that of their allies — must be deteriorated first. The Saudi-led air campaign is an important tool to this effect, and Riyadh could decide to wait and slowly choke Saleh and the Houthis' combat capabilities.

At the same time, a ground offensive could still be possible, even if it happens somewhere other than Aden. Saudi Arabia still has forces massed on Yemen's northern border, where skirmishes are already ongoing. These forces could be used to penetrate Yemen, with the possible intent to liberate Sanaa. Such an operation, however, would be even more costly than a defense of Aden, and Riyadh will not make this decision lightly. Even if they were to lose Aden, the Saudis would still maintain a wide range of options to deal with this crisis. How Saudi Arabia manages the coalition it has built to share the burden of responding to the situation in Yemen will be a critical aspect in shaping the overall strategy and levels of commitment the coalition is willing to accept.

Read the full analysis: The State of Play in Yemen

For more on Yemen, read: A Chronology of Yemen's Recent Instability