A meeting  between Chinese President Xi Jinping and Russian President Vladimir Putin in Beijing should have been an opportunity for China to encourage Russia to de-escalate tensions with Ukraine, the U.S. State Department's top diplomat for East Asia, Daniel Kritenbrink, said on Friday.

Such an approach is what the world expects from "responsible powers," Kritenbrink told reporters of the meeting that led to China and Russia proclaiming a deep strategic partnership.

Kritenbrink said the meeting and joint statement that followed reflected an approach that China and Russia had taken for some time, "namely to move closer together."

"The meeting should have provided China the opportunity to encourage Russia to pursue diplomacy and de-escalation in Ukraine." Kritenbrink said.

"If Russia further invades Ukraine and China looks the other way, it suggests that China is willing to tolerate or tacitly support Russia’s efforts to coerce Ukraine, even when they embarrass Beijing, harm European security and risk global peace and economic stability."

The China-Russia agreement marked the most detailed and assertive statement of Russian and Chinese resolve to work together - and against the United States - to build a new international order based on their own interpretations of human rights and democracy.

They pledged mutual protection of core interests - an apparent reference to Russia and Ukraine and Taiwan, a self-ruled island Beijing claims as its own.

The joint statement is also strongly critical of U.S. moves to stand up to China's growing power in the Indo-Pacific region through the AUKUS pact, under which the United States and Britain plan to provide Australia with nuclear-powered submarines.

It came as China's Xi hosted Putin on the opening day of the Beijing Winter Olympics. Washington announced a diplomatic boycott of the Games to protest what it describes as China's ongoing genocide against Muslim minorities.

On Thursday, the U.S. State Department warned Russia that a closer relationship with Beijing would not make up for consequences imposed in response to an invasion of Ukraine and that Chinese firms would face consequences if they sought to evade export controls imposed on Moscow in that event.