The incident came as world leaders worked to develop strategies to combat the terror group, which is also known as IS and calls itself the Islamic State. It has seized territory in both Iraq and Syria, and declared an Islamic caliphate. If the group is allowed to fester, it will threaten "our homeland," U.S. Defense Secretary Chuck Hagel warned Congress Tuesday.
U.S. military aircraft have targeted IS locations in Iraq. An airstrike Monday southwest of Baghdad appeared to be the closest yet to the Iraqi capital since the campaign began last month.
A statement from U.S. Central Command described the action as "the first strike taken as part of our expanded efforts beyond protecting our own people and humanitarian missions to hit IS targets as Iraqi forces go on offense, as outlined in the President's speech last Wednesday."
An IS "fighting position" that was firing on Iraqi security forces southwest of Baghdad was destroyed, the statement said.