WASHINGTON — Russia has deployed 28 combat planes in Syria, US officials said Monday, confirming the latest move in Moscow's increasing military presence in the war-torn nation.

"There are 28 fighter and bomber aircraft" at an airfield in the western Syrian province of Latakia, one of the officials told AFP, speaking on condition of anonymity.

A second official, also speaking on condition of anonymity, confirmed the figure, and added there were about 20 Russian combat and transport helicopters at the base.

That official also said Russia was operating drones over Syria, but did not give additional details.

Washington in recent weeks has expressed growing concern over Russia's increasing military presence in Syria to support President Bashar al-Assad.

The United States has warned that Russian military backing for the Syrian regime only risks sending more extremists to the war-torn country and could further hamper any effort at bringing peace.

Moscow, meanwhile, has been on a diplomatic push to get the coalition of Western and regional powers fighting the Islamic State group to join forces with Assad against the jihadists.

US Defense Secretary Ash Carter spoke with his Russian counterpart Sergei Shoigu on Friday, ending an 18-month freeze in military relations triggered by NATO anger over Moscow's role in the Ukraine crisis.

They agreed to continue discussions, which are crucial to lessen the risk of incidents involving coalition forces and Russian forces operating in the same air space.

The US-led coalition is carrying out almost daily strikes against the jihadists in Syria.

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