Russia’s deputy foreign minister, Andrei Rudenko, is in Beijing Sunday for a meeting with the Chinese foreign minister to secure the future of the China-Russia relationship and assure China’s leadership of the Kremlin’s durability.

The details of the meeting are unknown, but Mr. Rudenko is likely to appraise his counterpart of the domestic unrest in Russia. The timing of the visit, however, is telling.

Having just stood down a coup attempt, President Putin appears to have a shakier grip on power than at any time in his nearly quarter century in power. Communist China is watching.

In a terse statement on its website, the Chinese foreign ministry said that the two sides met to discuss “international and regional issues of common concern.” Clearly Beijing is trying to comprehend yesterday’s events, their effect on Putin’s grip on power, and what the impact on the Russia-China relationship will be.

Private military companies like Yevgeny Prigozhin’s Wagner group are a wildcard, an unknown in China, where the ruling Communist Party monopolizes power and groups like Wagner cannot exist under a nearly omniscient police state.

The coup’s rapid end “obviously narrowed the impact on Putin’s authority,” Hu Xijin, a Chinese political commentator for China’s Global Times, said on Twitter, though he added, “not to zero.”

The Chinese party has yet to comment on Wagner’s occupation of Rostov-on-Don or march toward Moscow, but Beijing undoubtedly sees developments to its west with unease.

An unstable Russia could pose a threat to China. The two countries share a long border. Both are autocratic countries with strongman leaders who see America as their number one adversary. Both are nuclear-armed.

An open civil war in Russia and violence spilling across the border into China would be bad. Regime change in Moscow — and new leadership friendly to the West along the countries’ 2,600-mile border — would be more threatening to China.

On the other hand, a relatively bloodless change of leadership in Russia, but one that is lukewarm toward China, would mean the loss of China’s most important strategic partner and further isolation.

Just days before Russia’s invasion of Ukraine, presidents Xi and Putin characterized the two countries’ relationship as a “no-limits friendship,” seen today as a tacit endorsement by Communist China of the Ukraine invasion.

Though the countries’ relationship is lopsided — Russia imports much more from China than it exports but has valuable knowledge of jet engine technology that the Chinese lack — Moscow seems to accept its status as a junior partner.

Bound, though, by their mutual opposition to the international system America built after World War Two, they are partners, nonetheless. Beijing has walked the line between voicing support for the Kremlin without upsetting European countries who have coalesced around their mutual suspicion of China and dislike of China’s unfair trade practices.

China has refrained from providing weapons and ammunition to Russia like the west has given Ukraine. The question now is if this policy would change if civil war erupted in Russia — how far would China go to preserve Mr. Putin in power if push came to shove?

Mr. Prigozhin’s abortive march on Moscow yesterday may well be round one of a larger Putin- Prigozhin rivalry. While Mr. Putin seems to have the reins of power firmly in hand, Beijing is watching.