With global tensions climbing over the year-long war in Ukraine, the Biden administration is warning China of non-specific "costs" if it wades into the conflict on Russia's side. 

State Department spokesman Ned Price said Thursday that China risks "peril" by sending guns into the warzone or helping Russia avoid Western sanctions.

Treasury Secretary Janet Yellen also pointed to "serious consequences" if China doesn't play ball, although it's unclear exactly what the punishment would look like.

The West has chafed at robust trade between Russia and China that has limited the impact of sanctions, and officials in the U.S. allege that China may soon begin supplying lethal aid to Russia -- a charge China vehemently denies.

China ventures peace?

China offered a peace plan on Friday, but the overture has been received with skepticism by Western governments that accuse China of supporting Putin's regime.

Biden's Secretary of State Antony Blinken told ABC Friday that China is trying to "have it both ways" by playing the role of peacemaker while indirectly supporting Russia's war effort. He doubled down on the claim that China is "contemplating lethal assistance."

"It's on the one hand trying to present itself publicly as neutral and seeking peace, while at the same time it is talking up Russia's false narrative about the war," he said.

China responds

Although China claims to be neutral, they have joined Russia in blaming the hostilities in Ukraine on the West, and China has said the U.S. is chiefly responsible for continuing to fuel the conflict with billions in military aid.

China's foreign ministry accused the U.S. of hypocrisy and "smearing" China by "falsely claiming that China might offer weapons to Russia."

“We have promoted peace talks in our own ways and played a responsible and constructive role in easing tensions and alleviating the crisis," Foreign Ministry spokesman Wang Wenbin said. "The U.S. is the biggest source of weaponry for the battlefield in Ukraine."

Tensions rising

China formally called for a cease-fire in Ukraine Friday and an end to all sanctions against Russia, as Biden marked the war's one-year anniversary by announcing new sanctions and another $2 billion in military aid for Ukraine.

Some of the new sanctions target Chinese companies that the administration says have been helping Russia.

The rising tensions between the U.S. and China come after President Biden pledged NATO's unwavering support for Ukraine during a trip to Europe this week, saying the West has Ukraine's back for "as long as it takes."

Vladimir Putin isn't backing down, either, from a conflict he has framed as a struggle for Russia's very survival.