Iraqi Prime Minister Adel Abdul Mahdi on Monday condemned U.S. airstrikes on bases of Iranian-backed Iraqi militia, a move that could plunge Iraq further into the heart of a proxy conflict between the United States and Iran.

The U.S. military carried out airstrikes on Sunday against the Kataib Hezbollah militia in response to the killing of a U.S. civilian contractor in a rocket attack on an Iraqi military base, officials said.

At least 25 militia fighters were killed and 55 wounded.