The U.S. military conducted an airstrike in southern Somalia on Sunday against a suspected militant leader, a U.S. military official told CNN.

The target was described by the official as a "senior leader" affiliated with al Qaeda and Al-Shabaab, al Qaeda's affiliate in Somalia.

The United States has not yet been able to determine whether the target was killed, the official said.

Last October, the elite U.S. Navy SEAL Team Six aborted a pre-dawn raid in southern Somalia to capture Al-Shabaab leader Ikrima after an intense firefight prevented them from reliably taking him alive, a senior U.S. official told CNN at the time.

In a second raid that same weekend, members of the U.S. Army Delta Force captured Abu Anas al Libi, an al Qaeda operative wanted for his alleged role in the deadly 1998 bombings of two U.S. embassies in Africa, during an operation in the Libyan capital of Tripoli.

The U.S. military official said Sunday's strike involved missiles. No U.S. troops were on the ground.

Al-Shabaab, designated a terrorist organization by the United States, has a relationship with al Qaeda that goes back several years. In 2012, the two groups effectively merged, said CNN national security analyst Peter Bergen.

Al-Shabaab hopes to turn Somalia into a fundamentalist Islamic state but has launched attacks in other countries as well.

In 2010, Al-Shabaab claimed responsibility for two suicide bombings in Kampala, Uganda, amid crowds of soccer fans watching televised screenings of the World Cup final. The bombings left 74 people dead.

The group said at the time the attacks were retaliation for Ugandan participation in the African Union Mission in Somalia, known as AMISOM. One AMISOM goal is to support Somali government forces in cracking down on Al-Shabaab.

Al-Shabaab has also mounted many smaller attacks against targets in Kenya, hurling hand grenades into nightclubs, restaurants and schools. The group has also kidnapped tourists and aid workers.

The group claimed responsibility for the September siege of the Westgate mall in Nairobi on September 21 that killed at least 67 people.

Al-Shabaab said the attack was retaliation for Kenya's involvement in the African Union effort against the group.

In recent months, Al-Shabaab's haven in south-central Somalia has been increasingly squeezed as Kenyan forces fight the group from the south and African Union forces come down from Mogadishu, the Somali capital.