Washington is committed to "working with the Iraqi government and leaders across Iraq to support a unified approach against ISIL's continued aggression," State Department spokeswoman Jen Psaki told reporters.
"We stand ready to provide any appropriate assistance," she added, condemning today's kidnapping of 48 people from the Turkish consulate in the northern Iraqi city of Mosul by militants from the Islamic State of Iraq and the Levant (ISIL).
"You can expect we will increase our assistance" to the Iraqi government, Psaki said, stressing that the United States has already expedited arms shipments to Iraq this year and ramped up training of Iraqi security forces.
The candidate to be the next US ambassador to Baghdad, Stuart Jones, said two days of coordinated attacks by the Islamic State of Iraq and the Levant "highlights just how dangerous this group is."
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US officials have warned that ISIL, which split from Al-Qaeda, poses a threat to the entire region, and is being fueled by arms and personnel coming out of the conflict in neighbouring Syria.
The United States has already pumped millions of dollars of military aid into Iraq following the withdrawal of all US troops.
In January, Washington sold 24 Apache attack helicopters to Baghdad as well as some 300 anti-tank Hellfire missiles and two of some 36 F-16 fighter aircraft, a Pentagon spokesman said. Some of the arms have been delivered and others should be on their way by the fall.
The last US troops left Iraq in December 2011, eight years after they deposed Saddam Hussein following the 2003 invasion ordered by then president George W. Bush.
"Security assistance, however, is only one element of our assistance and it is connected to intense political and economical engagement," Jones said.
And he vowed Washington would try to help an estimated half a million people who have fled the fierce fighting in Iraq this week.