Putin Sent Xi Birthday Greetings. Here Was the Real Message.

Birthday best wishes rarely come freighted with so much significance. But when it is Russia’s embattled president, Vladimir V. Putin, flattering his Chinese counterpart, Xi Jinping, even seemingly small gestures send a message to the world, not least to their Western rivals.

Mr. Putin sent Mr. Xi a congratulatory telegram when the Chinese leader turned 70 on Thursday, wishing his “dear friend” good health, happiness and success, further cementing the image of a personal bond between the two authoritarian leaders.

“It is difficult to overestimate the effort that you have made over many years to strengthen our comprehensive partnership and the strategic interaction between our countries,” Mr. Putin wrote.

The close relationship between the two leaders and their nations has been fundamental to Russia’s economic survival since it invaded Ukraine nearly 16 months ago. But it risks growing fraught over the long term, as Russia becomes increasingly reliant on China, while China takes a more measured approach to Moscow and seeks to win back some European support.

In Russia, China has been welcomed as an economic partner that is an alternative to the West, even amid fears among some that Moscow could become a vassal. China has supplied the isolated country with many products, as Western companies have pulled out of the market. It is Russia’s most important energy customer, buying more of its oil than any other nation and potentially becoming a greater consumer of its gas, now that sales to Europe have dried up. Those continued energy revenues have helped the Russian government fund the war.

In Beijing, Russia is regarded as a vital partner against an increasingly united and antagonistic West. But Russia’s need for economic and political support — and pleas for weapons for the battlefields of Ukraine — has also fueled anxieties that China is becoming too tethered to Mr. Putin’s war and is increasingly exposed to diplomatic damage from it.

In particular, China has become more concerned about alienating Europe, which is a much bigger trade partner than Russia and a key player in the rivalry between Beijing and Washington. The Chinese government has also sought to ease the escalating tensions with the United States, agreeing to hold two days of meetings with U.S. Secretary of State Antony J. Blinken in Beijing starting Sunday.

“It’s an awkward dance,” Joseph Torigian, an assistant professor at American University in Washington who studies Chinese and Russian politics, said in an interview, referring to the partnership between Moscow and Beijing. “You don’t want the West to think that they could split the partnership, but also the partnership is having real economic and reputational costs for China.”

Mr. Putin’s birthday wishes come as the St. Petersburg International Economic Forum, the annual Davos-like event in his hometown, provided a fresh demonstration of Russia’s deepening isolation as a result of its war on Ukraine.

The event had previously served as a showcase of the Russian market primarily to big European and American companies. This year, top Western executives were nowhere to be found. The event featured panels on the “dedollarization” of global trade and the economic potential of the Shanghai Cooperation Organization, a regional grouping that includes Russia and China.

But the Chinese presence at the forum has also been muted relative to past years, part of what appears to be an effort by Beijing to avoid being seen as a willing backer of Mr. Putin’s war.

The Chinese ambassador to Russia and the leader of a Chinese trade group were among the more prominent of slated Chinese guests. In 2019, Mr. Xi himself attended the forum, where he and Mr. Putin promoted their countries as guardians of free global trade. A string of top Chinese executives and officials also attended that year.

Despite a 41 percent surge in trade between Russia and China in the first five months of this year, Chinese companies have been wary of investing in Russia, in large part because of the risk of punishment from Western governments, especially since the war in Ukraine.

“There may even have been a contraction from prewar cooperation, because after all, the U.S. sanctions need to be taken into account,” said Xiao Bin, a foreign policy researcher in Beijing, referring to Chinese investment.

Many Russian corporate leaders, on the other hand, are quietly wary of China’s dominance.

“It was a nightmare of the Russian elites to get that dependent on China,” said Tatiana Mitrova, a research fellow at the Center on Global Energy Policy at Columbia University.

On the diplomatic front, Chinese officials have sought to improve China’s standing with Western European nations that have criticized the country for not using its influence on Russia to stop the war. Scholars in Chinese government institutes have become bolder in arguing that Beijing needs to show more clearly the limits to its partnership with Russia.

But Mr. Xi, in particular, appears determined to keep treating Mr. Putin as an esteemed peer, united by a shared conviction that the United States and its allies want to drastically weaken Russia and stymie China’s rise as a great power. The two leaders reaffirmed their countries’ partnership at a summit in Moscow in March. And they have used birthdays to signal their closeness since Mr. Xi became China’s leader in 2012, trading gifts including ice cream, an embroidered portrait of Mr. Putin, and a Russian “YotaPhone” for Mr. Xi.

Yu Bin, an expert on Chinese-Russian relations who is a senior fellow at East China Normal University in Shanghai, nonetheless cautioned against reading too much into the shows of bonhomie. “There is a personal touch, but I would not exaggerate that,” he said. “First and foremost, the pursuit of a normal relationship between the two large countries is paramount.”

Despite the camaraderie between Mr. Xi and Mr. Putin, there are limits to the partnership that they memorably said early last year was “without limits.”

Mr. Putin wants Beijing to commit to a proposed Power of Siberia 2 gas pipeline, which would help redirect Russian gas flows that historically have gone to Europe toward China instead, showing the world that the Kremlin retains big economic partners willing to fuel the Russian economy.

Beijing has been relatively silent about the project, possibly because signing on with public fanfare as conflict still rages in Ukraine would risk making China seem like an enthusiastic economic backer of Russia’s war.

“China doesn’t want to portray itself as helping fund Putin’s war chest,” said Alexander Gabuev, director of the Carnegie Russia Eurasia Center. “If you want to convince everyone you are a peacemaker, bringing additional revenue to Putin’s war chest is not a good thing.”

“The relationship is definitely of mutual interest,” Mr. Gabuev said. “But there is also an asymmetry built in. China is a bigger animal. It is a robust manufacturing, scientific power. Russia is mostly a one-dimensional economy. This now is a trend line on steroids.”

Over the longer term, there are concerns in Russia that Beijing could take advantage of Moscow’s weakened, distracted state to push for deals in energy, for instance, that are unfavorable to Moscow, or to expand Chinese influence in regions where they are rival powers, including in Central Asia and the Arctic.

Yet so far the Chinese leadership has proceeded carefully, working to avoid a perception that it is taking advantage of Moscow at a moment of weakness.

“I would say the Chinese are aware of Russian sensitivities, particularly in the past 10 to 15 years, and don’t want to, as we say in Chinese, drop a stone on someone already at the bottom of the well,” Mr. Yu said.

Joy Dong contributed reporting.