Updated

The U.S. military says it has killed four al-Shabab extremists in Somalia in what it calls airstrikes in self-defense.

A U.S. Africa Command statement on Tuesday says the extremists launched attacks on Somali troops and their U.S. advisers on Monday in a village near the port city of Kismayo.

The statement says Somali forces returned fire, killing several extremists, but the attack continued. The U.S. then conducted its strike, killing four fighters.

U.S. forces have carried out several airstrikes in Somalia in recent years, killing many al-Shabab leaders.

The extremist group is now mostly active in rural regions but continues to launch lethal attacks in many parts of this Horn of Africa nation, including the capital.