He said: “We are beginning a new Cold War, with the worst possible outcome a nuclear war between the US and Russia.
“Relations today between the US and Russia are comparable to the dark days of the Cold War. How could we have let that happen?”
Increasingly hostile relations between the US and Russia, North and South Korea and India and Pakistan have put the world on a knife-edge and with all of those countries possessing nuclear weapons, they could cause devastation at a moment’s notice.
Among the other speakers was former prime minister Tony Blair, who branded North Korea “abhorrent”.
He said: “We can threaten military action… But unless there are elements of which I am unaware in either the weakness of the North Korean defences or the strength of US capabilities, it is hard to think of a pre-emptive strike which would not result in catastrophic consequences.”
Mr Blair continued: “The sensible thing is to preserve the current agreement.”
He added that sticking to the agreement "means, for now at least, that Iran's nuclear program can be stalled”.
Mr Lavrov also told Mr Tillerson Moscow is demanding the US returns Russian diplomatic property seized in 2016 over suspected Russian interference in the general election.
The pair's phone call came just hours after Donald Trump's most senior general told the US Army to "stand ready" for war with North Korea.
General James 'Mad dog' Mattis warned it is impossible to tell what the future holds for the crisis, but urged US troops to be prepared for a confrontation with Kim Jong-un.