President Joe Biden will warn his Chinese counterpart Xi Jinping on Friday that he will face "costs" if Beijing rescues fellow authoritarian ally Russia from intense Western sanctions aimed at punishing Moscow's invasion of Ukraine.
The two leaders' first phone call since a video summit in November will be a chance to air differences as the United States spearheads an unprecedented pressure campaign on Russia, placing China in a geopolitical bind.
It's "an opportunity for President Biden to assess where President Xi stands," White House Press Secretary Jen Psaki said.
Trade rows and snarled international supply chains will be discussed, according to Psaki, but a big focus is expected to be the Western bid to force Russia from Ukraine, where President Vladimir Putin's invasion is in its fourth week.
Biden has successfully marshalled a tight Western alliance against Russia, while giving military support to Ukrainian forces.
But Beijing has refused to condemn Moscow and Washington fears the Chinese could switch to full financial and even military support for Russia, transforming an already explosive transatlantic standoff into a global dispute.
Not only could Beijing potentially help Russia weather crippling pressure on its banks and currency, but Western governments would then face the painful decision of whether or not to impose sanctions against China, likely prompting turmoil on world markets.
The White House was tight-lipped on whether Biden will threaten China with sanctions during his call, but some sort of response is on the table.
Biden "will make clear that China will bear responsibility for any actions it takes to support Russia's aggression and we will not hesitate to impose costs," Secretary of State Antony Blinken said.
He hoped China would use "whatever leverage they have to compel Moscow to end this war," the top U.S. diplomat said.
"Instead, it appears that China is moving in the opposite direction," Blinken said, adding he was "concerned that they're considering directly assisting Russia with military assistance."
- China 'balancing priorities' -
The Biden-Xi call comes after U.S. National Security Adviser Jake Sullivan and Yang Jiechi, the Chinese Communist Party's chief diplomat, held what the White House called a "substantial" seven hour meeting in Rome this week.
Against a backdrop of already intense tensions over Taiwan and trade disputes, the ability or failure of Biden and Xi to come to an understanding on the unfolding mayhem in Europe will reverberate widely.
Xi and Putin symbolically sealed their close partnership when they met at the February Winter Olympics in Beijing -- just before Putin launched his onslaught on Ukraine.
Since then, Beijing has stood out by refusing to join international outcry over the invasion, while taking the Russian line in blaming the United States and NATO for European tensions. Chinese authorities even refuse to refer to the invasion as a "war," again in keeping with Kremlin talking points.
But China has also tried to remain somewhat ambiguous, declaring support for Ukraine's sovereignty.
Under growing pressure to take a side, China will weigh clashing priorities, said Brookings Institution fellow Ryan Hass, a former advisor on China to president Barack Obama.
Despite the coziness with Moscow, China, the number two economy and world's biggest exporter, is tightly bound to U.S. and other Western economies. It also wants to play a leadership role in the world.
"China's and Russia's interests are not in alignment. Putin is an arsonist of the international system and President Xi sees himself as an architect for remaking and improving the international system," Hass said.
"President Xi is trying to balance competing priorities. He really places a lot of value in China's partnership with Russia but at the same time he does not want to undermine China's relations in the West."