The anti-Islamic State group coalition conducting airstrikes in Iraq and Syria has killed the ISIS militant believed responsible for an attack on U.S. troops in northern Iraq last month that left a Marine dead, it said on Sunday.

Militant Jasim Khadijah, a former Iraqi officer not considered a high-value target, was killed by a drone strike overnight in northern Iraq, coalition spokesman U.S. Army Col. Steve Warren told reporters in Baghdad.

"We have information [that] he was a rocket expert, he controlled these attacks," said Warren, referring to the shelling of a base used by U.S. troops near the town of Makhmour, located between Mosul and Kirkuk.

That attack killed Marine Staff Sgt. Louis Cardin and wounded eight others, all part of a company-sized detachment of fewer than 200 troops. They provide force protection fire to Iraqi army troops, who are making slow progress in a campaign to clear areas around Mosul, an ISIS stronghold.

Cardin's was the second combat death of an American service member in Iraq since the start of the campaign to fight the militant group in 2014.

Warren said five other Islamic State group fighters were killed in the airstrike.