The US says it has launched an air strike against militants from the Islamic State (IS) group in Iraq.
The Pentagon said American aircraft attacked artillery that was being used against Kurdish forces defending the northern city of Irbil.
US military aircraft conduct strike on ISIL artillery. Artillery was used against Kurdish forces defending Erbil, near US personnel.— Rear Adm. John Kirby (@PentagonPresSec) August 8, 2014
President Barack Obama authorised air strikes on Thursday, but said he would not send US troops back to Iraq.
The Sunni Muslim group IS, formerly known as Isis, now has control of large swathes of Iraq and Syria.
Iraq: Working with partners we've assessed the needs of 150,000 Iraqis in 27,000 families, to determine support needed— UN Refugee Agency (@Refugees) August 8, 2014
'CAREFULLY AND RESPONSIBLY'
According to the Pentagon statement, two F/A-18 aircraft dropped 500-pound laser-guided bombs on mobile artillery near Irbil.
Pentagon press secretary Rear Admiral John Kirby said IS had been using the artillery to shell Kurdish forces defending Irbil, where US personnel are based.
Speaking on Thursday, Obama said the Iraqi government had requested assistance and the US would act "carefully and responsibly, to prevent a potential act of genocide" against the Yazidi and Christian communities - both minority groups in Iraq.
Dr Marzio Babille, Unicef's representative in Iraq, said the Yazidis were in an extremely precarious situation because of the "very aggressive and brutal" IS militants.
FAA bans U.S. airlines from flying over Iraq due to "potentially hazardous situation" http://t.co/5j31X0Hsi8— Washington Post (@washingtonpost) August 8, 2014
He said there were many "logistical and strategic difficulties", but added that a humanitarian corridor needed to be established.