Rear Adm. John Kirby, the Pentagon’s press secretary, said in a statement late Monday only that “we are assessing the results of the operation and will provide additional information as and when appropriate.” But U.S. officials told NBC News that a military drone launched Hellfire missiles at at least two vehicles in a remote area of southern Somalia, with al-Shabaab’s top leader, Ahmed Abdi Godane, believed to have been the target. Military and intelligence officials were still working Monday night to confirm who may have been killed.