"We are not putting forward this intelligence to start a war, which has happened in the past... We are putting forward this intelligence to stop a war, and I think that it fundamentally gives it at the outset a different level of credibility," Sullivan said in an interview to the CNN when asked to present evidence to support the US claims of a Russian invasion.

At the same time, Sullivan said he could not predict the exact date of the start of the potential Russian attack, after the US President Joe Biden reportedly told the allies that it will be February 16.

"We cannot perfectly predict the day, but we have now been saying for some time that we are in the window and an invasion could begin, a major military action could begin by Russia in Ukraine any day now," he said.