A US drone strike killed more than 150 fighters when it struck a training camp for al-Shabaab fighters in Somalia who were preparing to launch a large-scale attack, according to the Pentagon.
Navy Captain Jeff Davis, a Pentagon spokesman, said the strike hit Raso Camp on Saturday.
He said the US was watching the camp for weeks and it appeared that the training was ending and the operational phase of a suspected attack was about to start.
He added that the training camp, about 120 miles north of Mogadishu, was destroyed.
The al-Qaida-linked al-Shabaab has been linked to a number of attacks, including the detonation of a bomb on board a commercial passenger jet last month that forced the plane to make an emergency landing in Mogadishu.