Russian President Vladimir Putin on Tuesday suspended his country's participation in the last remaining nuclear arms control pact with the U.S.

The decision was announced just a day before China's top diplomat Wang Yi was set to arrive in Moscow, where the situation in Ukraine will likely dominate the conversation. Also on Tuesday, China's Foreign Minister Qin Gang announced that Beijing is "deeply concerned" about the year-old conflict in Ukraine, which appeared to be "intensifying and even getting out of control."

"I am forced to announce today that Russia is suspending its participation in the strategic offensive arms treaty," Putin said Tuesday in announcing the break from the New START nuclear arms reduction treaty.

Signed in 2010, the New START treaty caps the number of strategic nuclear warheads that the U.S. and Russia can deploy.

Putin also said that Russia should stand ready to resume nuclear weapons tests if the U.S. does so, a move that would break a Cold War-era global ban on such tests. The move adds further tension to already strained relations between Russia and the U.S.

Secretary of State Antony Blinken called Putin's move "deeply unfortunate and irresponsible."

“Our relations have degraded, and that’s completely and utterly the U.S.’s fault,” Putin said.

As Russia continues its descent into a pariah state, China's recent attitude toward the ill-fated invasion seems to be souring, if slightly.

"We would like a political solution to provide a peaceful and sustainable framework to Europe," Wang said during a speech at the Lanting Forum on global security in Beijing. He added that the world was riven by disorder and wars and "peace-loving countries [should] bring the current hostilities to a halt as soon as possible."

Despite declaring a "no limits" partnership just weeks before Russia's invasion of Ukraine, China has now hit a block in its unequivocal support. As Xi Jinping mulls over his own territorial dispute, and the potential fallout from a Taiwanese invasion, Russia's mounting losses have dampened the outlook for global strongmen.

Russia's warming attitude toward the potential use of nuclear arms in the conflict is sure to be discussed between the allied nations as well, especially as top-level U.S. officials scramble to respond to Putin's decision on New Start.

"We remain ready to talk about strategic arms limitations at any time with Russia, irrespective of anything else going on, in the world or in our relationship. I think it matters that we continue to act responsibly in this area," Blinken told CNN.

Russia and the U.S. together hold 90% of the world's nuclear warheads.

Russia Ukraine China U.S.