In a major setback for al-Qaeda’s affiliate in East Africa, the Obama administration said Friday it had confirmed the death of a key Somali militant leader who had been targeted in an airstrike earlier in the week. The White House and Pentagon released statements asserting U.S. responsibility for killing Ahmed Abdi Godane, the leader of al-Shabab, a Somali jihadist movement that has become an increasing threat to neighboring countries, including Kenya and Uganda. Godane had bragged of masterminding an audacious assault by gunmen on a Nairobi shopping mall last year, killing dozens while keeping local security forces at bay for days. After receiving intelligence on the elusive Godane’s whereabouts, the U.S. military sent drones and other aircraft on Monday to an al-Shabab camp near the southern port of Barawe. They unloaded several Hellfire missiles and other munitions, flattening the camp and destroying a nearby vehicle. But with no U.S. troops on the ground to pick through the wreckage, Godane’s fate was not immediately clear. The Pentagon did not reveal in its statement how it was able to confirm Godane’s death.