IS push could take years: Kerry

US Secretary of State John Kerry said on Wednesday that an international coalition against the "Islamic State" (IS) militant group would most likely need to exist for years.

He was speaking at the beginning of a meeting of foreign officials in Brussels, who are seeking to bring down the IS insurgency. Launched less than three months ago, the coalition has more than 62 partners, Kerry said, including European, Arab, North American and Asian nations.

"We recognize the hard work that remains to be done," Kerry said at the NATO headquarters.

"Our commitment will be measured most likely in years, but our efforts are already having a significant impact."

Using an Arabic acronym for the IS, Kerry said: "The roughly 1,000 coalition air missions that we have flown have reduced Daesh's leadership and inflicted damage on its logistical and operational capabilities. No large Daesh unit can move forward aggressively without worrying about what will come down on it from the skies."

The IS has made significant territorial gains in recent months as part of a quest to establish a "caliphate" in northern Iraq and Syria. It's believed thousands of foreign fighters have flooded the two countries to join the militant group.

Kerry's comments came after the Pentagon announced overnight that Iranian fighter jets had struck IS miltants in eastern Iraq.

"We have the indications they have flown these missions in recent days in eastern Iraq," Pentagon spokesman Rear Admiral John Kirby said.

Kirby added that the strikes were not coordinated with the US nor the coalition of nations. Previous offers of help from Iran were rejected by the US. Washington is concerned that Iran, which backs Iraq's majority Shiite government, will provoke further resentment among its Sunni minority.

A spokesman for the Iranian foreign ministry, Marsieh Afcham, told news agency dpa that the Pentagon's statements were "not precise and thus not correct."

jr/ksb (dpa, AP)