President Barack Obama has authorized US forces to conduct air strikes against Sunni extremist militants in Iraq if they are needed to prevent a massacre of civilians.
"We can act, carefully and responsibly to prevent a potential act of genocide," Obama said, referring to a religious minority group besieged by fighters from the so-called Islamic State.
"I therefore authorized targeted air strikes if necessary to help forces in Iraq as they fight to break the siege and protect the civilians trapped there."
The United States has not carried out any air strikes in Iraq but is ready to do so after orders from President Barack Obama, an official said Thursday.
"No air strikes have taken place at this time, but we remain postured to take targeted military action should the situation warrant it," the US official said on condition of anonymity.
Another official, briefing reporters after Obama warned of the risk of "genocide" against Iraqi minorities, said that the United States would act if Islamist guerrillas threatened the key city of Arbil.
The official also said that the United States was prepared to take military action to "relieve the pressure" against the beleaguered Yazidi minority if Iraqi efforts do not work.
But the official said that the United States was not planning a "sustained campaign" against the extremists in the Islamic State movement, saying that Iraq bore the responsibility.
Abbott backs US airstrikes
Prime Minister Tony Abbott has backed the decision saying the terrorist group Islamic State, formerly known as ISIL or ISIS, had emerged as a major threat in Syria and Iraq.
"If it is allowed to succeed in carving out a terrorist state in the Middle East it will also pose a significant threat to international security," Mr Abbott said in a statement on Friday.
He understood the air strikes were intended to support US personnel located in Erbil and also to break the ISIL siege of Sinjar.
"The Australian government is extremely concerned by the threat posed by ISIL and the even greater threat it will pose if it succeeds in its latest offensive," Mr Abbott said.
"Therefore we strongly support President Obama's course of action."
He said it was no longer an evil terrorist group but a "highly potent insurgent army" capable of holding territory, imposing its "abhorrent form of government" and forging alliances with other extremist organisations.
Emergency UN meeting to be held
The UN Security Council is to hold an emergency meeting on Iraq, after Islamist militants seized the country's largest Christian town.
The meeting was requested by France, which expressed concern over the advance of Islamic State fighters and the seizure of Qaraqosh, in a new offensive that has driven tens of thousands of people from their homes.
The talks are scheduled to begin on Thursday evening, a diplomatic source said.
"France is very deeply concerned by the latest advances of (IS militants) in the north of Iraq and the taking of Qaraqosh, the biggest Christian city in Iraq, as well as by the intolerable abuses that were committed," French Foreign Minister Laurent Fabius said in a statement.
"Given the seriousness of the situation - the first victims of which are civilians and religious minorities - France is requesting an urgent meeting of the Security Council so the international community can mobilise to counter the terrorist threat in Iraq and support and protect the population at risk," he said.
In the latest advance, the Sunni extremist Islamic State extended its writ over northern Iraq and moved within striking distance of autonomous Kurdistan.
IS, which proclaimed a "caliphate" straddling Syria and Iraq in late June, moved into Qaraqosh and other towns overnight after the withdrawal of Kurdish peshmerga troops, residents said.
Religious leaders say IS militants have forced 100,000 Christians to flee and have occupied churches, removing crosses and destroying manuscripts.
Joining world alarm over the IS advance, Pope Francis called on the international community to protect the mostly Christian communities of northern Iraq fleeing a lightning advance by jihadist militants.
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