The Kremlin warned that it could use the lethal weapons “if western countries try to test our resolve”. Russian diplomat Alexander Trofimov listed two “hypothetical scenarios” which could trigger a nuclear response. Speaking at the nuclear non-proliferation conference on Tuesday, Mr Trofimov denied that Russia has threatened to use its nuclear arsenal against Ukraine.
He said this is “utterly unfounded, detached from reality and unacceptable”.
However, he said Russia could use nuclear weapons “in response to weapons of mass destruction or a conventional weapons attack that threatened the existence of the Russian state”.
He added: “None of these two hypothetical scenarios is relevant to the situation in Ukraine”.
However, he accused NATO countries of a “fierce hybrid confrontation” against Russia that now “dangerously balances on the edge of an open military clash”.
He added: “Such a move would be able to trigger one of the two emergency scenarios described in our doctrine.
“We obviously stand for preventing this, but if western countries try to test our resolve, Russia will not back down.”
The day before, US President Joe Biden had said he was ready to pursue a new nuclear arms deal with Russia, calling on Moscow to “act in good faith”.
The conference is the second time this week Russia has accused the US of playing a direct role in the Ukraine war.
A spokesperson for the Pentagon said it provided Ukraine with “detailed, time-sensitive information to help them understand the threats they face and defend their country against Russian aggression”.
Russia has previously accused the US of engaging in a “proxy” war with Ukraine.
Speaking in April, Russian Foreign Minister Sergei Lavrov said that the country’s decision to supply Ukraine with billions of dollars worth of arms meant that “NATO, in essence, is engaged in a war with Russia through a proxy and is arming that proxy”.
He added: “War means war.”