The presidents of Russia and Iran, facing increased domestic pressure from drawn-out wars, were set to rally with the leaders of China and India at a summit on Monday in Central Asia.

President Vladimir V. Putin of Russia and President Masoud Pezeshkian of Iran headed to Bishkek, the capital of Kyrgyzstan, for a two-day meeting of the 10-nation political and security grouping known as the Shanghai Cooperation Organization. The forum will allow Russia and Iran to demonstrate alternative sources of support as they work to defy Western efforts to isolate them.

Though it once counted only Russia, China and four Central Asian nations as members, the grouping expanded in 2017 to include India and Pakistan and more recently to add Belarus and Iran. In the process, it has become a growing counterpoint to Western-led political and security groupings.

At the center of the proceedings is the most powerful leader in attendance, President Xi Jinping of China. No nation has been more critical to Russia and Iran in sustaining their economies and war efforts than China. Mr. Xi has undermined efforts by the United States and its allies to pressure Russia and Iran economically, employing Beijing’s vast geopolitical and economic clout as the world’s largest importer of crude oil and exporter of consumer goods.

The wars have helped increase China’s already rising power. Mr. Xi’s biggest rival, the United States, has been distracted by the war in Iran and has pulled out some of its military forces from Asia and Europe. Last month, Mr. Xi was able to brush off threats by President Trump that the United States would inflict an “economic D-Day” on countries that provided Tehran a lifeline.

This week’s summit is a reminder of the limits of U.S.-led economic warfare. Both Russia and Iran have managed to maintain critical alliances outside the West that have come in handy at different stages of their conflicts. The two nations have managed to handle domestic fallout from the wars for longer than some Western officials had expected.

The leaders in attendance have helped Mr. Putin continue his war against Ukraine, which is now in its fifth year.

Not long after Mr. Putin launched the all-out invasion in 2022, Iran supplied Russia with Shahed drones and helped Moscow establish domestic production facilities for the weapons.

Central Asian nations have become critical import and payment routes for Russia, as Moscow gets around Western restrictions. Iran has turned to Central Asia as an alternative import route amid a U.S. blockade.

India, Kazakhstan and Belarus are among the countries that have stepped in to ship gasoline to Russia in recent weeks as Ukrainian long-range strikes have decimated Russian oil refineries.

India emerged as one of the biggest purchasers of Russian oil in the aftermath of Mr. Putin’s invasion. Though its imports dropped following pressure from Mr. Trump and new U.S. sanctions on Russian oil giants, the U.S. war against Iran roiled oil markets and pushed Indian suppliers to turn once again to imports from Russia.

China is the biggest importer of Russian and Iranian crude. For four and a half years, Beijing has kept Moscow supplied with everything from consumer goods like cars and clothes to critical electronics components that the Russian military needs for the production of drones and other weapons.

Mr. Xi’s relationship with Mr. Putin is increasingly one-sided in Beijing’s favor. Western sanctions related to Russia’s war with Ukraine have enabled China to stockpile discounted Russian oil, cushioning the blow of a blockade in the Strait of Hormuz.

Even the site of this week’s summit highlights China’s growing hand over Russia. Once a Soviet republic, Kyrgyzstan used to firmly be in Moscow’s sphere of influence. But China’s influence in the Central Asian nation has grown, and the five nations of Central Asia have banded closer together in response to Russia’s war against Ukraine.

In opening remarks before a meeting with President Sadyr Japarov of Kyrgyzstan on Monday, Mr. Xi said relations between Beijing and Bishkek had “made a leap forward” and that cooperation was “flourishing across all areas.”

Mr. Xi’s priority at the summit is to burnish his image as the leader of non-Western nations and push back against what he calls U.S. hegemony. Despite that, he will most likely be cautious about how much support he offers Iran.

The Chinese leader cannot afford to provoke Mr. Trump less than a month before he is scheduled to travel to Washington to extend a fragile economic truce between the United States and China. Before heading to the United States, Mr. Xi will travel to Egypt and India for state visits.

The series of trips leading up to his summit with Mr. Trump is aimed at casting Mr. Xi as a powerful statesman at a time when Mr. Trump has frayed U.S. relations globally, analysts said.

“Xi appears to see an opportunity to show that China has friends and options around the world at precisely the moment Washington is alienating many of its allies,” Julian Gewirtz, who served as the senior director for China at the National Security Council during the Biden administration and is now a scholar at Columbia University, wrote in a newsletter.

“Xi’s diplomatic offensive will aim to drive home a more specific and powerful point,” he continued. “Beijing can deepen its influence across Eurasia and the Global South, build institutions around its own priorities, and then arrive in Washington to be feted by the American president.”