US has said it is sending a warship into the Gulf to provide President Obama with military options should the situation in Iraq deteriorate further.
US Defence Secretary Chuck Hagel has ordered the USS George HW Bush, which carries dozens of fighter jets, to be moved from the North Arabian Sea, reported BBC Online.
Meanwhile, Iran says it could be prepared to work with the US to fight Sunni insurgents in Iraq.
The insurgents have seized several cities and are closing in on Baghdad.
Fighting under the banner of The Islamic State in Iraq and the Levant (ISIS), they regard Iraq's Shia majority as “infidels”.
Iraqi security forces, bolstered by an increasing number of Shia and Kurdish militiamen, are trying to take a stand in Salahaddin and Diyala provinces, to the north of the capital.
US President Barack Obama has said he will take several days to decide what action to take over Iraq, but insisted that no US troops will be deployed.
The aircraft carrier will be accompanied by the guided-missile cruiser USS Philippine Sea and the guided-missile destroyer USS Truxtun. They were due to arrive in the Gulf late on Saturday.
US Secretary of State John Kerry has called on Iraq's political leaders to put their differences aside to defeat the Islamist offensive.
Kerry urged the government to ratify recent election results without delay and stick to a constitutional time-frame to form a new government.
