The Pentagon confirmed on Friday that Ahmed Abdi Godane,  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.

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

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.

Abdi Ayante, director of the Heritage Institute for Policy Studies in the Somali capital of Mogadishu, said Godane’s death would be “a game changer in many ways for al Shabaab.”

Before the Pentagon confirmed Godane’s death, Ayante said, “What is likely to happen is a struggle for power.” He adds that,  fragmentation was also possible in the absence of a leader with Godane’s experience and ruthless approach to dissent.

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.