UN Secretary-General Antonio Guterres says the world is approaching a situation "similar" to the Cold War as tensions rise between the United States and Russia.

But Guterres said Thursday it's different in two important ways: There are more players in conflicts than during the two-superpower era and fewer communication channels set up to keep problems from escalating. He told reporters Thursday he is "very concerned."

The US other Western nations and NATO are expelling more than 150 Russian diplomats whom they consider spies, including a dozen posted to Russia's UN mission, over the poisoning of a former Russian spy in England.

Russia said Thursday it will expel an equal number of diplomats from those nations.