The Moscow terror attack shows the limits of the Russia-Iran partnership

A regional branch of the Islamic State has claimed responsibility for two recent terrorist attacks, each of which killed more than 100 people. Islamic State-Khorasan Province (ISIS-K) was behind both the attack at a Moscow-area concert hall on March 22 and the bombing of a memorial ceremony in southeastern Iran for Qassem Soleimani, commander of the elite Quds Force, in January.

This mutual threat could have further bound together Russia and Iran, two nations which have been deepening their ties during the war in Ukraine. Instead, it seems more likely to become a point of friction.

Although ISIS-K has claimed responsibility for the Crocus City Hall attack, Russian President Vladimir Putin characterized Ukraine as being complicit or involved. Russian investigators also have made baseless claims that the gunmen had links with Ukrainian nationalists.

Laying the blame on Ukraine may help Putin reinforce public support as his war enters its third year, but he risks alienating Tehran in doing so.

Since Russia invaded Ukraine in February 2022, Tehran and Moscow have increased their defense cooperation. Iran has become one of Russia’s key military suppliers, providing unmanned aerial systems and ballistic missiles. Last November, Iran announced that Russia would be supplying its air force with Su-35 fighter jets; in addition, Tehran ordered Mi-28 attack helicopters and Yak-130 combat trainer aircraft.

Russia also provided surveillance capabilities to help the Iranian regime quell the nationwide protests sparked by the death of 26-year-old Mahsa Amini in police custody in September 2022.

Russia and Iran are also working together to bolster their economies. They’ve been sharing knowledge on how to evade international sanctions, have facilitated private sector deals on oil and gas and are investing in a massive transcontinental trade route that would improve both countries’ access to foreign markets.

Despite all that, unresolved tensions linger beneath the surface, starting with competition for energy markets. Both countries have hydrocarbon-dependent economies, and they are locked in a competition to export oil to China — a contest that Russia, the larger oil producer, is well positioned to win, to the detriment of Iranian commodity sales.

The two nations are also jockeying for influence in the Caucasus. Armenia, dissatisfied with Moscow’s failure to intervene when Azerbaijan occupied the Armenian enclave Nagorno-Karabakh in September 2023, is seeking security guarantees beyond Russia. Iran has taken advantage of this opening, opening a new consulate in the country, staging military exercises on its border with Azerbaijan and committing to strengthened economic ties with Armenia.

The Israel-Hamas war has illuminated other key differences in Russia and Iran’s worldviews and strategic interests. Iran, of course, has long characterized Israel as one of its two primary enemies. Russia historically has cultivated a good working relationship with Israel — although it deteriorated following a rapprochement with Hamas after Oct. 7. Deployments of U.S. forces to the Mediterranean Sea, which are intended to deter Iran from widening the conflict, contribute to heightening Iranian threat perceptions. Russia, on the contrary, likely sees these deployments as a welcome diversion of U.S. attention and resources from the Ukraine war.

All this contributes to mistrust between Russia and Iran, even as they have grown more dependent on each other. Russia’s response to the Crocus City Hall attack risks exacerbating Iranian anxieties about their relative status in the relationship. It could also magnify divisions within Iran: Not all Iranian leaders have welcomed closer relations with Russia, and some are wary of Iran becoming too dependent on a foreign power. Moscow’s downplaying of the ISIS-K threat will likely reinforce a perception among some in Iran that Russian and Iranian interests are not aligned.

Growing military and economic ties between Russia and Iran pose a threat to U.S. and Western interests; however, their relationship remains largely transactional. The Ukraine war has incentivized them to paper over their disputes for now, but it has not erased significant differences in the two countries’ threat perceptions, worldviews and strategic priorities. These differences are not insurmountable, but they ultimately make it more difficult for Moscow and Tehran to forge a true strategic partnership.

Michelle Grisé is a senior policy researcher at RAND, a nonprofit, nonpartisan research institute. Her research focuses on Iran, Russian foreign policy and military strategy, South Asia, and international law.