The Kremlin said Monday a new Russian ambassador to the United States would be appointed, dismissing speculation that relations with Washington were being downgraded at the end of the term of the current envoy Anatoly Antonov.

The Siberian-born Antonov, 69, a career diplomat, had been head of the Russian embassy in Washington since 2017. He said in July that his assignment was coming to an end.

Kremlin spokesman Dmitry Peskov said President Vladimir Putin was not currently scheduled to receive Antonov, but added that an ambassador had the opportunity to report to the president daily.

Asked if the return of Antonov indicated that relations with Washington were being downgraded, Peskov said: "No, of course an ambassador will be appointed in a timely manner."

The current confrontation between Russia and the West over Ukraine is unparalleled in history and a mistake could lead to catastrophe, a senior Russian diplomat said on Thursday when asked about comparisons to the 1962 Cuban Missile Crisis.

The 2½-year-old Ukraine war, the biggest land war in Europe since World War Two, has triggered a major confrontation between Russia and the West, and Russian officials say it is now entering its most dangerous phase to date.