US President Joe Biden warned on Thursday that any country that supported Russia’s attack in Ukraine would be “stained by association,” after China refused to declare Moscow’s move an invasion and instead asked all parties to exhibit moderation.

Ukrainian soldiers fought Russian invaders on three fronts when Moscow launched a land, sea, and air assault on Ukraine, the largest attack on a European state since World War II.

Biden told reporters at the White House, where he announced severe new penalties against Russia coordinated with partners, said Russian President Vladimir Putin’s actions marked a perilous time for freedom throughout the world.

“Putin will be a pariah on the international stage. Any nation that countenances Russia’s naked aggression against Ukraine will be stained by association,” Biden said without naming China.

Asked if he was urging China to isolate Russia, Biden said: “I’m not prepared to comment on that at the moment.”

Biden said Putin’s action “betrays a sinister vision for a future of our world; one where nations take what they want by force.”

White House spokeswoman Jan Psaki told a later news briefing “this is really a moment for China, for any country, about what side of history they want to stand on here.”

She noted that Secretary of State Antony Blinken had spoken to his Chinese counterpart about Ukraine this week and that Biden was “certainly open to speaking with his counterpart,” referring to Chinese leader Xi Jinping.

However, she added: “I don’t have any prediction of that at this point in time.”

Some geopolitical analysts said Russia’s action could embolden China over Taiwan, a democratically governed island Beijing says is part of China and has vowed to reclaim by force, if necessary.

Russia attacked Ukraine three weeks after Putin met with Xi Jinping in the run-up to the Beijing Winter Olympics that ended on Sunday. The two announced a strategic partnership aimed at countering U.S. influence and said they would have “no ‘forbidden’ areas of cooperation”.

Ahead of Biden’s remarks on Ukraine, Chinese foreign ministry spokeswoman Hua Chunying called on “all sides to exercise restraint to prevent the situation from getting out of control,” but bridled at journalists’ characterisation of Russia’s actions.

“This is perhaps a difference between China and you Westerners. We won’t go rushing to a conclusion,” she said.

“Regarding the definition of an invasion, I think we should go back to how to view the current situation in Ukraine. The Ukrainian issue has other very complicated historical background that has continued to today. It may not be what everyone wants to see.”