US President Joe Biden on Friday warned his Chinese counterpart that Beijing would pay a steep price if it supports Russia's invasion of Ukraine.

During the phone call with Chinese President Xi Jinping, Biden laid out the "implications and consequences" if Beijing backed Russia's attack, according to the White House.  

"The president underscored his support for a diplomatic solution to the crisis," the White House said. "The two leaders also agreed on the importance of maintaining open lines of communication, to manage the competition between our two countries."  

The almost two-hour call between Biden and Xi comes at a time of deepening acrimony between the US and Russia.

White House spokeswoman Jen Psaki said the conversation had not been about "carrots" or incentives to persuade Xi from assisting Russia in its war with Ukraine.

"The president laid out very clearly what the implications would be if they provided material support," Psaki told reporters.

What did China say?

In Beijing's readout of the call, Xi told Biden that the war in Ukraine must end as soon as possible.

"The top priorities now are to continue dialogue and negotiations, avoid civilian casualties, prevent a humanitarian crisis, cease fighting and end the war as soon as possible," Xi told Biden on the video call.

All parties should jointly support the Russia-Ukraine dialogue and negotiations while the United States and NATO should also conduct talks with Russia to solve the "crux" of the Ukraine crisis and resolve the security concerns of both Russia and Ukraine, Xi said.

How could China come to Russia's aid?

Washington this week told its Asian and European allies that US intelligence had determined that China had signaled to Russia that it would be willing to provide military support for the campaign in Ukraine.

Beijing had also promised financial backing to help stave off the impact of severe sanctions imposed by the West, US media reported.

Washington fears if the Chinese side switches to full financial and military support for Russia, it would turn an already explosive trans-Atlantic standoff into a global dispute.

The West would then face the painful decision of how to strike back at the world's second-biggest economy, likely prompting turmoil on international markets.

Washington has also accused China of sending mixed messages after Chinese state-owned banks appeared to pull back from financing Russian activities, according to a senior Biden administration official.

But there have also been public comments by Chinese officials who expressed support for Russia being a strategic partner.

In an attempt to improve US-China relations, White House national security adviser Jake Sullivan and senior Chinese foreign policy adviser Yang Jiechi met in Rome earlier this week for seven-hour talks.

The US and China have been at loggerheads for years over trade, Beijing's military provocations against Taiwan, human rights abuses and the Hong Kong pro-democracy movement.

Will Sino-Russian ties endure?

Xi and Russian President Vladimir Putin met in early February, weeks before the invasion, with the Russian leader traveling to Beijing for the start of the Winter Olympics.

During Putin's visit, the two leaders issued a 5,000-word statement declaring limitless "friendship."

Despite the coziness with Moscow, China — the world's biggest exporter — is tightly bound to the US and other Western economies. It also wants to play a leadership role in the world.

Beijing offers some support to Kyiv

Beijing has also tried to remain somewhat ambiguous, declaring support for Ukraine's sovereignty.

China's ambassador to the country on Monday was cited as saying: "China is a friendly country for the Ukrainian people. As an ambassador, I can responsibly say that China will forever be a good force for Ukraine, both economically and politically."  

mm/wd (AFP, AP, Reuters)