WASHINGTON (Reuters) – The United States has carried out an air strike in Somalia, killing more than 150 fighters with the al Qaeda-linked Islamist group al Shabaab, following U.S. intelligence on preparations for a large-scale militant attack, the Pentagon said on Monday.

The weekend strike using both manned and unmanned drone aircraft targeted al Shabaab’s “Raso” training camp, a facility about 120 miles north of the capital Mogadishu, the Pentagon said.

The U.S. military said it had been monitoring the camp for several weeks before the strike and had gathered intelligence, including about an imminent threat posed by those in the camp.

“We know they were going to be departing the camp and that they posed an imminent threat to U.S. and to Amisom, African Union mission in Somalia forces, that are in Somalia,” said Pentagon spokesman Captain Jeff Davis.

Davis declined to disclose any specific information the United States might have about the group’s intended target.

Al Shabaab could not be reached for comment.

Somalia’s Foreign Minister Abdusalam Omer said the Somali intelligence agency had provided information about the camp to the U.S. in the runup to the attack.

“There has to be intelligence on the ground for this to happen. Our intelligence had helped,” Omer told Reuters.

The al Qaeda-linked al Shabaab was pushed out of Mogadishu by African Union peacekeeping forces in 2011 but has remained a potent antagonist in Somalia, launching frequent attacks in its bid to overthrow the Western-backed government.

The group, whose name means “The Youth,” seeks to impose its strict version of sharia law in Somalia, where it frequently unleashes attacks targeting security and government targets, as well as hotels and restaurants in the capital.

Al Shabaab was also behind deadly attacks in Kenya and Uganda, which both contribute troops to an African Union peacekeeping force in Somalia.

Omer said the U.S. drone strike was a major blow to al Shabaab.

“It’s a big victory for fighting terrorism,” Omer said. “Instead of al Shabaab attacking civilians, it was a military target was hit and there was a high success rate.”

Davis said as many as 200 fighters were believed to be training at the Raso camp at the time of the strike and expressed confidence there were no civilian casualties.

“Their removal will degrade al Shabaab’s ability to meet the group’s objectives in Somalia, which include recruiting new members, establishing bases and planning attacks on U.S. and Amisom forces there,” Davis said.

No U.S. forces on the ground participated in the strike.

“It was an air operation,” Davis said.

(Additional reporting by Drazen Jorgic in Nairobi; Editing by Bernadette Baum and Ralph Boulton)