The Pentagon confirmed on Friday, Sept 5, that Ahmed Abdi Godane, a leader of the al Shabaab Islamist group, was killed in a U.S. airstrike in Somalia this week, calling it a "major symbolic and operational loss" for the al Qaeda-affiliated militants, Reuters reported.

"We have confirmed that Ahmed Godane, the co-founder of al Shabaab, has been killed," Rear Admiral John Kirby, the Pentagon's press secretary, said in a statement.

Since taking charge of al Shabaab in 2008, Godane had restyled the group as a global player in the al Qaeda network, carrying out bombings and suicide attacks in Somalia and elsewhere in the region, including the Sept. 21, 2013, attack on the Westgate shopping mall in Nairobi, Kenya, that killed 67 people.

Godane publicly claimed responsibility for the Westgate attack, saying it was revenge for Kenyan and Western involvement in Somalia and noting its proximity to the anniversary of the Sept. 11, 2001, attacks on the United States.

His death leaves a gap in al Shabaab's leadership and was seen as posing the biggest challenge to the group's unity since it emerged as a fighting force eight years ago.

U.S. forces struck Godane's encampment in south-central Somalia with Hellfire missiles and laser-guided munitions on Monday, but the Pentagon did not confirm his death until Friday, saying it was still assessing the results of the airstrike, according to Reuters.

U.S. President Barack Obama, attending a NATO summit in Wales, mentioned the confirmation to reporters, saying: "We released today the fact that we have killed the leader of al Shabaab in Somalia." He also noted the United States has worked persistently to degrade the group's operations.

Somali President Hassan Sheikh Mohamud confirmed Godane's killing, saying U.S. forces conducted the airstrike with the full knowledge and agreement of Somalia's government.