Germany, Italy, Britain and the United States have said they are ready to send arms to bolster the capabilities of Iraqi Kurds fighting ISIL militants in northern Iraq, and Washington has carried out several air strikes on ISIL positions there.

But there has been no known move to target ISIL inside Syria, where they seized some areas of the north and east during its foreign-backed war before storming across much of northern Iraq, declaring a faked "caliphate" straddling the two countries.

The Netherlands, a NATO member and close U.S. ally, has airlifted more than a million euros worth of humanitarian aid to northern Iraq, where ISIL advances have displaced over one million people, and said it might supply weaponry too.

"Everyone who is now calling for a stronger approach against ISIS in Iraq must realize that it will only be successful if we are ready to take on ISIS in Syria as well," Timmermans said, using another acronym for ISIL.

"Otherwise there is no point because it would simply shift to Syria ... Solutions for Iraq won't be sustainable if we don't also find a solution in Syria," he told journalists in The Hague.

Several Western governments warned this week that ISIL, which carried out a gruesome execution of captive U.S. journalist James Foley and posted a video of it online, poses a threat to Europe and America as well.

NJF/NJF