"Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and 'smart!' You shouldn't be partners with a Gas Killing Animal who kills his people and enjoys it!" Trump wrote on Twitter.

Trump's message comes one day after Russia vetoed a US-drafted resolution at the United Nations Security Council to set up a panel to identify the perpetrators of Saturdays' alleged toxic gas attacks in Douma.

Russia has said its military specialists found no evidence of a chemical attack, and suggested that rebels staged or spread rumors of an attack to pin the blame on Damascus.

In an earlier Wednesday tweet, Trump said that there was "So much Fake News about what is going on in the White House. Very calm and calculated with a big focus on open and fair trade with China, the coming North Korea meeting and, of course, the vicious gas attack in Syria."

Just before Trump's tweets, the Kremlin on Wednesday urged restraint in Syria, saying that countries should avoid taking action that could further destabilize the war-torn country.