Obock, Djibouti

They arrive daily by the hundreds now. Frustrated university graduates unable to find jobs at home; drought victims who’ve seen their livestock perish; victims fleeing violence spawned by religious or tribal conflict.

Two months ago, it was perhaps only several dozen a night, every one of these men and, increasingly, women, arriving on foot, sometimes having walked for months to reach this seaport. So eager are they to cross the Bab el Mandeb, a dangerous stretch of water separating them from the Arabian Peninsula, that they will embark on journeys that can seem almost biblical.

Known as the “gateway to grief,” the strait’s treacherous waters have swallowed more than 3,700 African migrants since 2006. Across the 28-kilometer strait lies Yemen, a country ravaged by bitter conflict. But to these job seekers—overwhelmingly Ethiopian, with a few Somalis, Sudanese and Eritreans—the conflict is no deterrent. If anything, it has become an important selling point for those arranging passage.

“Saudi Arabia is their destination. Many are returning to jobs they had there before,” says Ali Abdallah Al-Jefri, who directs the International Organization for Migration’s (IOM) Migrants Response Center here. Human smugglers tell the migrants that because of the raging violence in Yemen, “now is a good time to try to go back to Saudi Arabia,” Mr. Al-Jefri says. Instead, it’s the worst time.

Take Dawit Deresseh, an Ethiopian migrant. Mr. Deresseh, 30 and landless, had already crossed Djibouti twice in the past 12 months. He made one trip last year to a construction job in Saudi Arabia, but was repatriated with IOM’s help after losing his arm in a car wreck. He explained that he was in a smuggler’s vehicle with 26 other pilgrims when it struck a land mine near the Saudi border. “All 27 came from Ethiopia,” he said. Everyone else was killed. Nonetheless, within months of returning to Ethiopia, he was back again to cross the Bab el Mandeb, so desperate are he and his family for a regular income.

With the world’s attention on the million-plus migrants and refugees streaming across the Mediterranean from Syria to the European Union, the deadly route running through Djibouti can seem almost a sideshow. It will soon take center stage. Many of these migrants—already about 10,000 have been counted since January, compared to about 80,000 for all of 2014—are part of a growing population of vulnerable men, women and children who have disappeared upon leaving Djibouti. Some have died at sea trying to enter Yemen, including 44 confirmed drowned so far this year. Others have been kidnapped or tortured. The exact numbers are still unclear.

Further complicating matters: Because any African labor crossing Yemen is, by definition, unregulated, governments of the region simply don’t know how many have successfully made the journey. Until humanitarian organizations like IOM gain access to them, details on the migrants’ conditions will remain murky. But what we do know is that thousands of migrants have already been kidnapped by smuggling gangs operating across the Yemeni countryside, holding men and women for ransom.

In March, after IOM helped 300 Ethiopians return from Yemen, many of the them told us of the hardships they endured at the hands of kidnappers. “Ahmed” told of brutal torture and raping and killings. “Ali” related how his siblings in Saudi Arabia had to pay the kidnappers 10,000 Saudi riyal ($2,668) for his release. But he considers himself fortunate, lamenting how others didn’t share his fate, describing the inhuman cruelties he witnessed.

But even under the protection of organizations like ours, migrant safety can’t be guaranteed. Last month, armed men entered our center in Hodeidah firing their weapons, killing a 16-year-old migrant when a bullet pierced the wall he was hiding behind.

Making matters worse, many migrants end up as pawns in a propaganda war, with both sides to the Yemeni conflict claiming the other is arming these outsiders as mercenaries. As a result, upon being intercepted these migrants will languish in government facilities, often without sufficient food, medical attention or proper sanitation, until they are released for lack of funds to care for them.

While it’s no secret that mercenaries are operating in Yemen, we don’t believe either side is recruiting destitute, weak and abused Ethiopian migrants. Many make this perilous crossing simply to return to jobs they once held, after having been expelled due to changes in work-permit regulations—a common occurrence in the migrant world whenever authorities promise to crack down on irregular workers.

While few migration emergencies match Yemen for the severity of the terror being inflicted on its victims, what’s happening in this region is part of a growing world-wide scourge of violence wherever migrants roam. Wherever governments permit unregulated migration to fester, regulation is reduced to the whims of smugglers, often violent criminals who value profits over human rights and human lives. Migrant passage everywhere should be legal, safe and secure for all.

Mr. Abdiker is the director of the department of operations and emergencies at the International Organization for Migration.