The Pentagon is confirming that a key Islamic State mastermind was killed in an airstrike in Syria late last month.

The Islamic State group had already announced Abu Mohammed al-Adnani's death near al-Bab. U.S. officials initially said they had targeted him, but were trying to confirm the strike had actually killed him.

Al-Adnani was one of the group's most powerful figures. He led the strategy to conduct attacks abroad by recruiting foreign fighters, forming militant cells in Europe and inspiring lone wolves to launch their own assaults.

Pentagon press secretary Peter Cook said the successful strike is one in a series of recent operations to take Islamic State leaders off the battlefield, making it harder for the group to operate.