Jake Sullivan looks flushed and his jaw is clenched. Across from President Joe Biden’s National Security Adviser, over a row of ferns at a matching table draped in blue cloth, sits China’s senior foreign affairs official Yang Jiechi, his mouth frozen in a sanguine smile. The official photograph released by China’s state-run news agency of the two men sitting face to face on March 14 in Rome is a snapshot of how Beijing wants to be seen at this moment as China’s sometime ally Russia continues its deadly invasion of Ukraine: as a confident, emerging power facing a frustrated and worried United States.

The reality is more complicated. Russia’s President Vladimir Putin is hoping China’s leader Xi Jinping will see Russia’s invasion of Ukraine as another step forward for the two countries’ broader effort to push back against the world’s democracies. Russia is courting China’s support of its assault on Ukraine and hopes China will prop up Moscow’s faltering economy battered by sanctions. But if China further backs Russia’s aggression with significant monetary help or—even more unsettling—weapons, the blowback from the U.S. and European countries could threaten China’s long-term effort to rise as the dominant global power.

What China decides to do about Russia’s needs could mark a turning point in both the war in Ukraine and U.S.-China relations, and the outcome of China’s choice will define what a new global order looks like. Will China continue to try to reshape the current global economy in its image by participating in it? Or will China join Russia behind a new Iron Curtain of sanctions, cut off from the U.S. and Europe and left to navigate a new monetary system and trading framework?

Jin Mamengni—Xinhua/AlamyYang Jiechi, left, a member of the Political Bureau of the Communist Party of China Central Committee and director of the Office of the Foreign Affairs Commission of the CPC Central Committee, meets with U.S. National Security Advisor Jake Sullivan, right in Rome on March 14

“This is really a crucial moment and potentially a turning point,” says Bonnie Glaser, director of the Asia program at the German Marshall Fund of the United States. “They really are siding with the Russians. They are more closely aligned with the Russians than they’ve ever been.”

China and Russia have occasionally had a strained relationship over the past several decades. Moscow and Beijing fought a border war in 1969 along the edge of China’s northeast territory, and the two countries have never developed strong person-to-person ties across their shared 2,500 miles of border. As China has risen in global influence, Russia’s leadership have resented the prospect of becoming a client state of Beijing.

But China’s leaders are now leaning toward Moscow much more heavily than they did when trying to appear neutral following Putin’s seizure of Crimea in 2014. When Xi and Putin met at the opening of the Beijing Olympics on Feb. 4, the two agreed their countries’ relationship would have “no limits” and “no wavering,” according to a Chinese government description of the meeting. That was two weeks before Russian tanks rolled into Ukraine.

This has presented the Biden Administration with a delicate and growing challenge in how to talk to China about its assistance to Russia. The seven hours of talks between Sullivan and Yang inside the Rome Cavalieri hotel were “intense” and “reflecting the gravity of the moment,” a senior Administration official said, adding that the two officials had an “extensive conversation” about Russia’s war in Ukraine. Sullivan made it clear that the U.S. and European allies would consider cutting off Chinese financial institutions involved in backing Russia’s war financially, said a person familiar with the discussions.

Broadly, Xi Jinping has calculated that the U.S. is in decline and Western democracies have failed, Glaser says, and that Russia is one ally that can work alongside China to create a different international system that’s more favorable. But with Russia’s violent effort to take Ukraine, that assessment comes with considerable risk for China. If Russia emerges weaker from its war in Ukraine, and China backed it, China could suffer major economic backlash. China relies heavily on its trading relationships with European countries and has worked hard to prevent Europe from restricting trade. “That would be huge, if China ends up with a vast amount of countries around the world that are aligned against it because it has sided with Russia,” Glaser says.

Convincing European powers to punish China could be a tall order for President Biden, who’s had to work hard to convince Europe to limit its financial and energy ties to Russia. Biden is set to travel to Europe next week to meet with NATO allies, and China’s degree of support for Russia will surely come up in those meetings. U.S. officials want to prepare allies for how to respond if China begins contributing more financially or militarily to Russia. Meanwhile, Xi showed the importance he puts on keeping lines of communication open with European powers when he joined a video call with French President Emmanuel Macron and German Chancellor Olaf Scholz on March 8 to talk about the war in Ukraine.

This moment has put on a collision course two competing objectives of China’s foreign policy, says David Shullman, a former senior U.S. intelligence analyst on East Asia. China wants Russia to be its partner in building a new global order, but it also wants to be viewed as a “responsible power” that can someday lead the current one, or at least be at the center of a new system of global governance and connectivity, Shullman says. If China provides Russia with drones, surface to air missiles, or other weapons, “It would very clearly demonstrate that we have a break in what we expected out of the world order,” Shullman says. “It would be clear that China had very firmly sided with Russia against the democratic world and against developed democracies.”