Russia's Vladimir Putin and China's Xi Jinping are expected in Central Asia's Kyrgyzstan on Monday for a two-day summit, also attended by Iran's, Pakistan's and India's leaders.
Around a dozen heads of states will head to the Kyrgyz capital Bishkek to mark 25 years of the Shanghai Cooperation Group (SCO).
The group brings together Russia, China, India, Pakistan, Iran, four Central Asian countries and Belarus.
Putin and Xi have previously taken the opportunity at SCO summits to articulate their vision of a multipolar world and present a united front against the West.
It takes place four-and-a-half years into Ukraine war and six months into the war between Washington and Tehran. Iran will be represented by its president, Masoud Pezeshkian.
Putin, Xi, Pezeshkian as well as India's Narendra Modi and Pakistan's Shehbaz Sharif are due to take part in a plenary session chaired by Kyrgyz leader Sadyr Japarov.
Putin is also expected to hold separate bilateral talks with Iran's Pezeshkian and China's Xi, among other leaders, Kremlin spokesman Yuri Ushakov said.
Russia and Iran, both subject to extensive international sanctions, have strengthened their military and economic ties during the war in Ukraine, while US President Donald Trump has warned Moscow and Beijing against providing arms to Iran.
Putin's meeting with Pezeshkian comes days after the CIA's director John Ratcliffe made a rare trip to Moscow, with US media speculating he could have discussed Ukraine and Iran with his Russian counterparts.
The SCO has historically focused on economic issues. It gained momentum in recent years under Moscow's and Beijing's leadership.
On top of its 10 members, it now has 15 "dialogue partners", including Türkiye, Saudi Arabia and Qatar. It also has two observer countries: Afghanistan and Mongolia.
The SCO's founding declaration says the group is "not an alliance directed against other states".
Real and trade wars
The Bishkek summit takes place as some SCO members are in the midst of real wars — the Ukraine and Iran conflicts — or trade wars, with the imposition of US tariffs on Chinese and Indian goods.
This month, the US slapped secondary sanctions on Iran's trading partners in the sectors of gold, technology, digital assets, aviation, and maritime transport, aiming to cripple the Iranian regime.
Washington also threatened Iran's allies with sanctions.
China, a major importer of Iranian oil, responded by saying it will "firmly defend" its interests.
Iran, living under sanctions since its 1979 revolution, has regularly said it will not cave to economic pressure.
But Pezeshkian has acknowledged his country faces "economic difficulties".
Iran only joined the bloc in 2023.
Mohammad Hassan Najmi, an international relations expert, told the AFP news agency that Tehran "believes its membership and active participation in these alliances can enable it to circumvent US and European sanctions".
But concrete benefits of the group are uncertain, he said, as "in times of crisis, these alliances have rarely allowed Iran to resolve its difficulties".
