Vladimir Putin has called the US airstrikes on Syria an 'illegal act of aggression' in a furious response to the military action.
The Russian President warned of grave damage to relations between Washington and Moscow which are already 'in tatters'.
Putin believes that the missile strikes on a Syrian air base broke international law and have seriously hurt US-Russia relations.
The Russian leader regarded the U.S. action as 'aggression against a sovereign nation' on a 'made-up pretext' and as a cynical attempt to distract the world from civilian deaths in Iraq, Putin's spokesman Dmitry Peskov was cited as saying.
U.S. officials said they informed Russian forces ahead of the missile attacks and that they took pains to avoid hitting Russian troops at the base, saying there were no strikes on sections of the base where Russians were present.