Any attempt to get Ukraine into Nato will run into a “buzz saw” in Washington unless Europe pays for it, a top diplomat for Donald Trump has said.

Putin has said repeatedly that he is prepared to negotiate an end to the war, which first began in 2014, but that Ukraine would have to accept the reality of Russian territorial gains, which are currently about 20% of its land. He also refuses to accept Ukraine joining Nato, the military alliance of Western countries.