World News

WASHINGTON — An American Special Operations forces soldier was killed and four others were wounded on Friday in an attack in southwestern Somalia against fighters for the Islamic extremist group the Shabab, three Defense Department officials said. The casualties were the first to have been publicized in Africa since an ambush in Niger in October.

The American forces were alongside Somali troops at a small outpost near the town of Jamaame when they came under small arms and mortar fire, Defense Department officials said on Friday.

The American team was backed up by armed surveillance aircraft overhead, but it could not determine the location of the mortar fire in what one official called “a very quick engagement” by the militants. The Shabab, an affiliate of Al Qaeda, claimed responsibility for the attack; it has been fighting American forces in East Africa for more than a decade.

In a post picked up by the SITE Intelligence Group, which monitors online extremist message boards, the Shabab said that its fighters had struck a joint American-Somali base on the outskirts of Kismayo, mounting what it called a “fierce attack.”

The roughly 500 American troops in Somalia are mostly composed of a number of Special Operations units, including Army Green Berets, Marine Raiders and Navy SEALs spread across the country.

Friday’s fight, the extremist group said, came a day after the Shabab overran a Somali National Army base near Baidoa and ambushed other Somali soldiers in the Huriwa district of Mogadishu, the capital.

In a statement on Friday evening, the United States Africa Command said that one of the four injured Americans received medical care in the field, while the remaining three were evacuated. They were among a large force of 800 Somali and Kenyan soldiers conducting a “multiday operation” around 200 miles southwest of Mogadishu when the attack occurred.

“The mission’s objectives were to clear Al Shabab from contested areas,” Africom said.

The attacks come as the American military looks to draw down counterterrorism forces in Africa as part of a larger Pentagon plan to pivot its focus on combating Russia, China and other great powers.

It was the second American combat death in Somalia in the past 13 months. Last May, a member of the Navy SEALs was killed and two other American service members were wounded in a raid that the Pentagon initially described as an “advise, assist and accompany” mission.

Defense Department officials initially said that Somali government troops had led that operation, and the Shabab militants had attacked American forces that were hanging back. But American military leaders later acknowledged that the Navy SEALs were operating alongside the Somali military when they launched the raid.

In October, an ambush in Niger killed four American soldiers, their interpreter and four Nigerien troops. That attack has opened a debate in Washington over the American military mission in Africa. The Pentagon has carefully monitored the spread of radical Islamic jihad across Africa but insisted that American troops are there to train and team up with local forces, not necessarily to fight.

Over the past year, American military officials have expressed new concerns about the Shabab, which was responsible for one of the deadliest terrorist attacks on African soil when it struck a popular mall in 2013 in Nairobi, Kenya. Officials worry the extremist group is in the middle of a resurgence after losing much of the territory it once held in Somalia and many of its fighters in the last several years.

In September 2014, American officials said they believed a drone strike crippled the group by killing its leader, Ahmed Abdi Godane, who at the time was one of the most wanted men in Africa. Another strike followed in March 2015, when Adan Garar, a senior member of the Shabab, was killed in his vehicle.

But the Shabab no longer appears to be crippled by the deaths of Mr. Godane and Mr. Garar. In the past two months, Shabab militants have claimed responsibility for attacks that have killed more than 150 people, including Kenyan soldiers stationed at a remote desert outpost and beachcombers in Mogadishu.

Two months ago, the group carried out multiple coordinated attacks against African Union peacekeeping forces, killing dozens of Ugandan soldiers.

On Monday, The New York Times reported that a sweeping Pentagon review of elite United States commando missions is likely to result in a sharp cut — by as much as half over the next three years — in Special Operations forces in Africa.

Defense Secretary Jim Mattis and Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, have ordered the military’s Special Operations and Africa Commands to present a range of options by mid-June to balance rising security challenges — which also include North Korea and Iran — with vital counterterrorism operations.

More than 7,300 Special Operations troops are working around the world, many of them conducting shadow wars against terrorists in Yemen, Libya, Somalia and other hot spots.