WASHINGTON – A senior Al-Shabab militia leader was killed by a U.S. airstrike in southwestern Somalia, according to U.S. and Somali officials.

Somalia's National Intelligence and Security Agency identified the slain man Tuesday as Abdishakur, also known as Tahliil. The agency said he was the head of an Al-Shabab unit believed responsible for suicide attacks in Mogadishu.

The Pentagon said Monday it had launched an airstrike against a "senior Shabab leader" near the town of Saakow, northeast of the Al-Shabab stronghold of Kismayo. Officials at that time did not identify the target or say whether the strike succeeded.

A U.S. defense official, who was not authorized to speak on the record, confirmed Tuesday that Abdishakur was the target of the attack and was killed.

Pentagon spokesman Rear Adm. John Kirby said that the military was still assessing results but had "no indications whatsoever so far of any civilian causalities or collateral damage as a result of the strike that we took."

The airstrike underscored the Obama administration's attempts to help contain the Islamist insurgency that has threatened the U.S.-allied government in Mogadishu and has spilled over into Kenya.

Recent lethal attacks

Al-Shabab, which controls a large swath of rural Somalia, has been trying to regain power since it was driven out of Mogadishu and the port city of Kismayo by African Union troops in 2011 and 2012.

In recent months, Al-Shabab has claimed responsibility for lethal attacks on coastal resort areas in Kenya as well as a Dec. 3 suicide bombing of a United Nations convoy near Mogadishu's airport.

A U.S. airstrike in early September killed Al-Shabab's top commander, Ahmed Abdi Godane, as he traveled in a vehicle south of Mogadishu.

U.S. officials believed Godane, 37, was responsible for steering Al-Shabab into closer alignment with Al-Qaida and its more global, anti-Western direction after he took over the militia in 2008. The group had previously focused attacks on Somali government forces. The U.S. declared the militia a terrorist organization in 2008.

Under Godane, Al-Shabab gunmen conducted executions and other violence against those who didn't share their harsh interpretation of Islam. The group alienated moderate Somali Muslims and accelerated the flight of refugees.

Setbacks for Al-Shabab

The attacks by the U.S. follow a series of military setbacks that Al-Shabab has suffered since African Union-backed Somali government troops pushed the militants to withdraw from Mogadishu in August 2011. Since then, the army has forced the insurgents to relinquish control of about 70 percent of southern and central Somalia.

Last week, Zakariya Ismail Hersi, a senior Al-Shabab commander wanted by the U.S., surrendered to the Somali authorities. The State Department in 2012 offered a $3 million reward for information leading to the capture of Hersi, describing him as head of the group's intelligence operation.

Somali security forces on Tuesday handed over Hersi to the authorities in Kenya, said Adan Mohamed, a Somali security official.