The White House on Sunday implored China to condemn Russia's invasion of Ukraine, as Moscow's attack against its neighbor escalated and Russian President Vladimir Putin placed nuclear forces on high alert.

According to White House press secretary Jen Psaki in an interview with MSNBC, China has implemented some measures set by the U.S. and its allies against Russia as a result of the invasion and voiced in favor of Ukrainian sovereignty last week.

She did, however, state that Beijing should do more.

"This is not a time to stand on the sidelines. This is a time to be vocal and condemn the actions of President Putin and Russia invading a sovereign country," White House press secretary Jen Psaki said in an interview with MSNBC.

She added that President Joe Biden has not talked with Chinese President Xi Jinping recently, but she did not rule out a future contact.

"But there's also important steps for the Chinese leadership to look at themselves and really assess where they want to stand as the history books are written," Psaki said.

Last week, Biden threw only a veiled jab at China when Beijing rejected calling Moscow's move an invasion and encouraged all parties to exhibit restraint.

"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.

Some geopolitical analysts believe Russia's move will embolden China in its claim to Taiwan, which it claims is part of China and has threatened to reclaim by force if necessary.

Three weeks after Putin met with Xi Jinping in the run-up to the Beijing Winter Olympics, which finished on Sunday, Feb. 20, Russia launched an invasion of Ukraine. They announced a strategic relationship geared at opposing U.S. influence, with "no 'forbidden' areas of cooperation," they said.

Psaki's remarks on Sunday were more explicit, coming only hours after Putin ordered his military command to activate Russia's nuclear deterrent in the face of a massive Western response to his conflict in Ukraine.

China is Russia's most important trading partner in terms of both exports and imports, purchasing one-third of Russia's crude oil exports in 2020 and supplying it with manufactured goods ranging from cell phones and computers to toys and apparel.

On top of the penalties imposed last week, the U.S., Britain, Japan, Canada, Australia, and the EU imposed more sanctions on Moscow, including Germany's decision to block a $11 billion gas pipeline from Russia.