(NewsNation) — Russia has suffered several defeats in the Ukraine war, leading to new threats of nuclear war.

The National Security Council’s John Kirby says threats to Russia aren’t coming from the west or NATO, but instead coming from Russia’s own actions.

An ally of President Vladimir Putin warned NATO on Thursday that a defeat of Russia in Ukraine could trigger a nuclear war, while the head of the Russian Orthodox Church said the world would end if the West tried to destroy Russia.

In a post on Telegram, former Russian President Dmitry Medvedev, who serves as deputy chairman of Putin’s powerful security council, said, “The defeat of a nuclear power in a conventional war may trigger a nuclear war. Nuclear powers have never lost major conflicts on which their fate depends.”

Striking a similar tone at what he described as an anxious time for the country, the head of the Russian Orthodox Church said in a sermon for Epiphany that trying to destroy Russia would mean the end of the world.

Medvedev said NATO and other defence leaders, due to meet at Ramstein Air Base in Germany on Friday to talk about strategy and support for the West’s attempt to defeat Russia in Ukraine, should think about the risks of their policy.

Putin casts Russia’s “special military operation” in Ukraine as an existential battle with an aggressive and arrogant West, and has said that Russia will use all available means to protect itself and its people.

The rhetoric, which Kirby called “reckless” and “irresponsible,” is intended to deter the U.S.-led NATO military alliance from getting even more involved in the war, on the eve of a meeting of Ukraine’s allies to discuss sending Kyiv more weapons.

“Russia is the aggressor here, Ukraine pose a threat to no one, let alone Russia a year ago, and they were invaded. They were attacked from the air, from the sea, and on the ground from Russia last February,” Kirby said. “They are the aggressor. And if they’re worried about threats to the homeland, then one of the things they can do is simply leave Ukraine, call it a day and take their troops out. They can end this war today.”

Kirby said the United States government will continue to talk to the Ukrainians about what they need.

“Clearly tanks are important, particularly in the fighting that they’re doing right now. The Brits have offered tanks, other nations are now considering tanks. And we think that’s a good thing for Ukraine, and we’re grateful for the support that other nations want to provide. As for our own tanks, or advanced capabilities, you know, we’re still going to continue to evaluate this going forward, but not every tank is exactly the same,” Kirby said.