A member of Russian President Vladimir Putin's powerful Security Council on Tuesday warned that the more destructive the weapons that the West supplied to Ukraine, the higher the risk of "nuclear apocalypse."
Russia, which has more nuclear weapons than any other state, has repeatedly said the West is engaged in a proxy war with Russia over Ukraine that could escalate into a much bigger conflict.
The United States has committed $37 billion in security assistance to Ukraine since Putin sent troops into Ukraine in February last year.
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"The more weapons are supplied, the more dangerous the world will be," former Russian president Dmitry Medvedev, who serves as deputy chairman of the Security Council, told Russian news agencies while on a trip to Vietnam.
"And the more destructive these weapons are, the more likely the scenario becomes of what is commonly called a nuclear apocalypse," Medvedev was quoted as saying by the Russian state news agencies TASS and RIA.
The West says it wants to help Ukraine defeat Russia but has repeatedly insisted that it does not want to trigger a direct military confrontation between the US-backed NATO military alliance and Russia.
The Russian military said on Tuesday it had routed militants who had penetrated the Belgorod region on Russia's border with armored vehicles, killing more than 70 "Ukrainian nationalists" and pushing the rest back into Ukraine.
Medvedev said the attackers were "scumbags" who should be exterminated "like rats."
"Responsibility ... is carried by the Kyiv regime, and ultimately by its sponsors overseas - that is, Washington and the countries of the European Union, along with affiliated states like Britain and others," Medvedev said, according to TASS.
"This is their responsibility, direct and immediate."