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.