As Russian President Vladimir Putin confers with China's President Xi Jinping in Moscow, the visit signifies more than a celebration of the so-called "no limits" partnership between the two powers.
It's also a pivotal meeting poised to deepen the gap between the East and West, and just the latest in a series of stress tests on the relationship between Beijing and Washington -- one already pushed to a near-breaking point.
Even though Biden administration officials anticipated Xi would journey to Moscow, they still describe the summit as a setback for the U.S.-China relationship and say they'll be watching the visit closely to see if Beijing intends to supply Moscow with military aid -- a potentially game-changing development for the war in Ukraine, and one that could bring the simmering tensions between the U.S. and China to a boil.
ABC News spoke with experts and officials about the challenges Russia and China's alliance poses to the U.S., the Biden administration's approach to Beijing, and how world leaders can avoid potentially catastrophic escalation.
Xi and Putin: Neighbors, partners, and 'leaders for life'
While Xi's three-day state visit is a welcome signal of support for Putin's war effort, it also comes at a critical time for the Chinese leader as he tightens his authoritarian grip, formally locking down an unprecedented third term as China's president.
The two men already have highlighted their personal bond, calling each other "dear friend" as they also touted their strategic partnership and increasingly ominous opposition to the West.
"China and Russia are more aligned than they've been since the 1950s," said Brad Bowman, senior director of the Center on Military and Political Power at the Foundation for Defense of Democracies.
Despite being a close ally of the Kremlin and echoing many of its talking points on Ukraine, Xi has sought to project his country's involvement in the conflict as a peace mission, promoting his 12-point proposal for a cease-fire.
Secretary of State Antony Blinken on Monday said the dovish motivations claimed by Beijing were merely a façade, calling it "a stalling tactic at best" or an attempt "to facilitate an unjust outcome."
"It would enable Russia to further entrench positions in Ukraine. And a ceasefire now, without a durable solution, would allow President Putin to rest and refit his troops and then restart the war at a time more advantageous to Russia," Blinken said. "The world should not be fooled by any tactical move by Russia, supported by China or any other country, to freeze the war on its own terms."
Sources in the Biden administration have also said that China could still choose to supply Russia's military with lethal aid, a possibility they've warned of since last month and a development the U.S. has said would prompt steep consequences for Beijing.
"We'll see what they come out of this meeting talking about," White House spokesperson John Kirby said Monday of Xi and Putin.
"China has not condemned the war but they haven't provided lethal weapons. They haven't participated in sanctions the way we obviously would have preferred them to do," he added. "They have made their own sovereign decisions and largely, at least tacitly, many of those decisions have come down on the side of Russia here."
Kirby said Xi Jinping should play a "constructive role" and reach out directly to Ukrainian President Volodymyr Zelenskyy, saying, "China ... we believe ... should hear directly from the Ukrainians, and not just from the Russians."
Scott Kennedy, a senior adviser at the Center for Strategic and International Studies, says that shared goal has emboldened China to expand its power on the global stage, seeking to edge out the U.S.
"What's new lately is the greater willingness to directly name the U.S. as the source of tensions in the world and just be much more direct, suggesting that they are gradually moving in a direction which they don't see the possibility of improving the relationship and that themselves may take more drastic actions," he said.
A fine line between 'competition' and conflict
Publicly, the Biden administration streamlines its stance toward China into a single catchphrase: "Invest, align, compete."
Invest refers to invigorating American institutions and align means drawing closer to allies and partners. But "compete" seems open to interpretation, and perhaps liable to escalation.
"When I look at the threat from China, it's unprecedented in modern American history, I don't think we've ever confronted a threat that combines a hostile ideology, an economy roughly the size of her own, and a military that is increasingly capable, and in some ways, more formidable than ours in key capabilities," said Bowman.
Kennedy says that while Washington as a whole has shifted in response to Beijing's increasingly bellicose stance, there's not a consensus on how to move forward.
"Is the goal to sort of harden the West against China but assume that we're going to be coexisting indefinitely? Or do you see this conflict is such an existential challenge that the U.S. goal has to be to fundamentally change the nature of the Chinese regime to make it more compatible with the international system?" he questioned.
In certain ways, the Biden administration is hedging its bets, straddling both approaches.
As one example, it has repeatedly stressed the need for open lines of communication with China but provided Beijing with little advance warning before announcing an agreement to provide Australia with nuclear subs, a maneuver aimed at countering China in the Indo-Pacific. Likewise, Beijing has used a similar double-edged strategy in many areas.
"The Chinese say that they believe in cooperation and mutual respect, but they're doing a lot of things which are inconsistent with those principles," said Kennedy. "We're locked into now is a vicious cycle in which both sides actually have relatively mirrored views of the other's motives and blame, and both have a relatively fatalistic view about the trajectory of their relationship."
A new Cold War?
While the Biden administration has repeatedly denied the U.S. and China are entering a new Cold War, Bowman says Washington should acknowledge how strained their ties have become.
"It's information warfare, it's economic warfare. It's basically every kind of warfare you can but we're not quite yet to the point where we're shooting at each other yet," he said. "But I'm worried it's not going to stay cold."
Bowman says avoiding that depends on a number of factors, such as moving quickly to arm Taiwan in order to deter a potential invasion from mainland China and continuing to build and reinforce a strong coalition of Western allies.
Kennedy agrees with the administration's stated goal that "guardrails" need to be installed to avoid the relationship from veering into a catastrophic war, but notes that China has been hesitant to adopt and use tools like direct hotlines between the countries.
Chances for direct diplomacy are also limited. After a Chinese surveillance balloon was spotted over the U.S., President Biden said he intended to hold a call with his counterpart Xi, but that has yet to be scheduled. That same incident prompted the administration to indefinitely postpose Blinken's trip to Beijing, dashing another chance for engagement.
"We have no good mechanisms in place to manage a crisis," said Kennedy. "I'm worried that we are heading toward the possibility of an unintentional conflict that could spiral out of control very quickly."