A US air strike has killed more than 150 al-Shabab militants in Somalia, the Pentagon says.
Spokesman Captain Jeff Davis said the strike hit a training camp where a "large-scale" attack was being planned.
"We know they were going to be departing the camp and they posed an imminent threat to US and [African Union] forces," Captain Davis said.
"Initial assessments are that more than 150 terrorist fighters were eliminated," he added.
Mr Davis said the strike, by both drones and manned aircraft, took place on Saturday and targeted Raso Camp, a training facility about 120 miles (195km) north of the capital, Mogadishu.
The camp had been under surveillance for some time, according to Mr Davis. "There was a sense that the operational phase was about to happen," he said.
He said the group had neared the completion of specialist training to conduct "offensive operations", but did not give any details about the alleged plans.
Al-Shabab, an affiliate of al-Qaeda, was pushed out of Mogadishu by African Union peacekeeping forces in 2011 but has continued to launch frequent attacks in its bid to overthrow the Western-backed government.
The group has said it carried out a string of recent attacks including a twin bombing at a busy restaurant in the Somali city of Baidoa last month.
Also on Monday, the Australian navy said it had seized a huge cache of weapons on a fishing boat off the coast of Oman that was apparently heading for Somalia.
Grenade launchers, machine guns, and 2,000 assault rifles were concealed under fishing nets, a Navy spokesman said.
Tomi Oladipo, Africa Security Correspondent
Crippling al-Shabab is top of a recently-announced US military strategy for Africa, which also includes addressing the situation in Libya and containing Boko Haram in West Africa. With drones from its nearby bases in neighbouring Djibouti, the US has succeeded in striking hard at the heart of al-Shabab operations, including killing Ahmed Godane, the leader of the jihadi group, in 2014.
The jihadis have since learned that they are often watched by surveillance aircraft and so they tend to meet under trees to avoid detection. This method has its limits, as this latest incident shows. They cannot train at will without being seen.
Al-Shabab maintains its determination to establish its rule over Somalia, hence its resilience and increasingly sophisticated attacks. The group is suspected to be behind an explosion at a security checkpoint at the Beledweyne airport which could have been more lethal had the explosives got aboard an airliner.
Major al-Shabab attacks in 2016
28 February - on a restaurant and busy junction in Baidoa killing at least 30 people
26 February - on Mogadishu's SYL hotel killing nine people
21 January - on a restaurant at Mogadishu's Lido beach killing 20 people
15 January - on a Kenyan base in el-Ade that Somalia's president said killed at least 180 soldiers