Story highlights The U.S. has expressed concern about Russia's military buildup in Syria

Obama and Putin are due to meet on Monday for the first time in nearly a year

(CNN) Iraq says it has reached a deal to share intelligence with Russia, Iran and Syria in the fight against ISIS militants.

The announcement on Saturday from the Iraqi military cited "the increasing concern from Russia about thousands of Russian terrorists committing criminal acts within ISIS."

The news comes amid U.S. concerns about Russia's recent military buildup in Syria and would appear to confirm American suspicions of some kind of cooperation between Baghdad and Moscow.

A U.S.-led coalition has been carrying out an aerial bombing campaign against ISIS positions in Iraq and Syria since last year. But now Russia is upping its presence in the region.

U.S. President Barack Obama is scheduled to meet with Russian President Vladimir Putin on Monday for the first time in nearly a year to discuss Moscow's plans in Syria.

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