The U.S. military says it killed four members of the extremist group al-Shabab during a counterterrorism operation in Somalia this week.

The U.S. Africa Command says Monday's strikes came in response to an attack by a "large group of armed al-Shabab fighters" on the joint operation by the U.S. and Somalia.

The U.S. says the two strikes near Tortoroow were made in self-defense.

The United States has used drone strikes against al-Shabab in this Horn of Africa country. The U.S. earlier this year confirmed that a drone strike killed senior al-Shabab military commander Abdullahi Haji Da'ud in May.

Somalia's homegrown al-Shabab extremist rebels are linked to al-Qaida and have carried out a series of attacks in the capital, Mogadishu, in recent months.