An airstrike in Syria targeted Iranian-backed Iraqi militia groups.
It killed at least one person and injured others, according to Iraqi officials.
The Pentagon says the strike was in retaliation for a rocket attack earlier this month in Iraq that killed one civilian contractor and injured a U.S. service member.
The department says the action was a "proportionate" response.
"We're confident and in the target that we went after, we know what we hit. And we're confident that that target was being used by the same Shia militia that conducted the strikes," said Defense Secretary Lloyd Austin. "I'm really proud of the men and women in our force who carried out the strike, as you would expect, they performed in a very professional manner and we're grateful for their service."
Defense Secretary Lloyd Austin says he recommended the action to President Biden and the president authorized the strikes Thursday morning.
The Biden Administration recently said it would be willing to have discussions with Tehran about rejoining the Iran nuclear deal.