Iraq said it was suspending flights between Baghdad and the northern cities of Irbil and Sulaimaniya for two days starting on Monday due to military traffic from Russia's air campaign in neighboring Syria.

Iraq's civil aviation authority said in a statement the decision was made "to protect travelers and because of the crossing of cruise missiles and bombers in the northern part of Iraq launched from the Caspian Sea."

Russia began launching cruise missiles from long-range bombers and from warships in the Caspian last month, passing over Iran and Iraq and covering a distance of some 1,500 km (900 miles) to reach their targets.

It was not immediately clear if Baghdad was expecting an increase in such activity this week. Iraq announced intelligence and security cooperation last month with Russia, Iran and Syria to counter the threat from Islamic State.

Moscow also uses bombers from Russian air bases to launch air strikes it says were requested by Syrian President Bashar Assad. It contends its main target is Islamic State militants who control large swaths of Syria and Iraq, but it has been accused of hitting other targets, including territory occupied by Western-backed rebels.

U.S. officials said last month four missiles launched from Russian warships in the Caspian Sea had crashed in Iran, but Russia insisted they had reached their targets in Syria.

The terrain-hugging Kalibr cruise missiles, which NATO has codenamed Sizzler, fly at an altitude of 50 meters (164 feet) and are accurate to within 3 meters, according to the Russian Defense Ministry.

A U.S.-led coalition has also been bombing Islamic State targets in Iraq and Syria for more than a year.