GETTY Vladimir Putin has sent 4,000 troops to Syria to fight ISIS

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The figure has doubled since Moscow began airstrikes against the notorious terror group at the end of September, according to US officials. They also claimed the number of bases used by Mr Putin's men in the war-torn nation has grown. Hundreds of ISIS jihadis are thought to have already been wiped out – along with the group's arms supplies.

The Russian foreign ministry refused to comment on the size of Mr Putin's contingent yesterday. But there are no Russian troops in combat roles in Syria, according to a spokesman for the Kremlin. He added that forces are guarding Russia's bases in the west of the country – and working with the Syrian military.

AFP Putin has come to blows with the US over the Syria crisis

The US officials also claimed several Russians have been killed – but failed to give exact numbers. The only death reported by the Russian government is a serviceman who committed suicide. Washington has strongly criticised Mr Putin's intervention in the Syria crisis, accusing the Russian president of trying to prop up president Bashar al-Assad.

The fight against ISIS Fri, November 18, 2016 The battle against ISIS militants (also abbreviated as Daesh, ISIL, IS and Islamic State) continues in the Middle East. Play slideshow Getty 1 of 183 Forces battle against ISIS