US State Department "will hold Iran responsible for the actions of its proxies that attack Americans," it said in a press briefing yesterday.
Last week, a rocket attack on a US airbase next to Erbil's international airport killed one civilian contractor and injured several others, including a US service member. The Guardian of Blood Brigades, which is known for its affiliation with the Iranian-backed Iraqi Hezbollah group, claimed responsibility for the attack.
Tehran condemned efforts to link it to the attack.
US spokesperson Ned Price added in his remarks that "the rockets fired in recent attacks on the coalition and citizens of Iraq, including this attack I referenced, are Iranian-made and Iranian-supplied."