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.
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.
In June, IS took control of the city of Mosul. Earlier this week, its fighters seized Qaraqosh, Iraq’s biggest Christian town.
The advance of IS also forced tens of thousands of people from the Yazidi community – another minority group in northern Iraq – to leave their homes and seek shelter on a nearby mountain.
The air strike is the first time the US has been directly involved in a military operation in Iraq since American troops withdrew in late 2011.
US Secretary of State John Kerry said the world needed to wake up to the threat posed by the IS group.
Its “campaign of terror against the innocent, including the Yazidi and Christian minorities, and its grotesque targeted acts of violence show all the warning signs of genocide,” he said.
‘Carefully and responsibly’
Speaking from the White House on Thursday, President Obama said “America is coming to help” the people of Iraq.
He accused IS fighters of attempting the systematic destruction of entire populations.
At the same time, he announced that US military planes had already carried out air drops of food and water, at the request of the Iraqi government, to the many displaced Yazidis who are in need of supplies.
Britain and France have also pledged humanitarian support, with the UK sending £8m ($13.5m) of emergency aid.
The United Nations says it is working on opening a humanitarian corridor in northern Iraq to allow stranded people to flee.
He said there were many “logistical and strategic difficulties”, but added that a humanitarian corridor needed to be established.
Meanwhile all US airlines and a growing list of other carriers are not flying over Iraq due to the situation.
Back in June, when Isis took over Mosul, Iraqi Prime Minister Nouri Maliki requested US air strikes to halt the militants’ advance – but Washington did not intervene.
Analysts say the relentless advance of IS fighters, together with the continuing failure of Iraqi politicians to agree on a new government, after an inconclusive election in April, may have swayed Mr Obama into deciding to act now.
Mr Maliki has faced calls from Sunni Arab, Kurdish and some Shia Arab leaders to step down because of his handling of the crisis.
But as leader of the bloc that won the most seats in April’s parliamentary elections, Mr Maliki has demanded the right to attempt to form a governing coalition.
Some reports suggest that he may have been forced to offer assurances that he would step down in return for military assistance from the US.