United States-Russian relations are "worse now" than ever, "and that includes the Cold War," President Donald Trump wrote today on Twitter.

"Our relationship with Russia is worse now than it has ever been, and that includes the Cold War. There is no reason for this. Russia needs us to help with their economy, something that would be very easy to do, and we need all nations to work together. Stop the arms race?" Trump tweeted.

In another tweet, Trump also warned Russia about supporting Bashar al-Assad in Syria, and said US missiles "will be coming" in retaliation for an alleged chemical weapons attack on civilians.

"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 shouldnt be partners with a Gas Killing Animal who kills his people and enjoys it!," he said on Twitter.