British Prime Minister David Cameron says that NATO leaders condemn the "barbaric and despicable acts" carried out by Islamic State militants and that threats by the extremist group will only harden their resolve to stand up for their values.
U.S. Secretary of State John Kerry called for a plan to counter the militant organization to be prepared in time for the UN General Assembly later this month.
He urged 10 allies to contribute in some form towards countering the threat from Islamist militants.
Kerry and Cameron spoke during a NATO summit in Wales on September 5.
A Western official said NATO would help coordinate security assistance for Iraq.
Islamic State fighters who have seized large swaths of northern Iraq and Syria have been accused of executing hundreds of Iraqi soldiers and carrying out massive abuses against religious and ethnic minorities.
The militants recently beheaded two U.S. journalists and have threatened to kill a British hostage.