Iran’s twelve-day war with Israel has pushed Tehran even closer to Moscow and led to new cooperation agreements, including increased weapons  supplies and closer cooperation in the nuclear sector.

Iran’s reliance on Russia has grown significantly in the wake of its brief but intense conflict with Israel and the United States in June, but the relationship is becoming increasingly one-sided, according to a new paper by Nikita Smagin for the Carnegie Endowment for International Peace.

Despite initial expectations that Moscow’s refusal to assist Iran militarily during the twelve-day war would chill relations, Tehran has since moved closer to Russia as one of its few key security partner options. Iran has been expanding cooperation in military, nuclear, energy and infrastructure sectors as it looks for allies in the face of possible renewed attacks by Israel.

“If anything, the balance in the relationship is once again shifting in Russia’s favour,” Smagin wrote, noting that Iran now views Russia as “an indispensable partner,” while the Kremlin is able to act “more selectively and assertively.”

Leaked documents from Russian defence conglomerate Rostec suggest that Moscow plans to supply Iran with 48 advanced fifth-generation Su-35 fighter jets. Russian military aircraft have reportedly begun flying regularly from Irkutsk, where the jets are produced, to Iran—suggesting the deal is wider than just the Su-35.

The UN and EU have renewed arms sanctions under the nuclear deal's "snapback" mechanism, but the Kremlin has made it clear it will ignore sanctions on Iran.

Nuclear cooperation is also expanding. Tehran initially said Russia would build five new nuclear power plants, later raising that number to eight. Moscow has confirmed a $25bn contract to construct the Hormoz Nuclear Power Plant and is working with Iran on small-scale reactor designs. However, Smagin noted that “Russia’s statements have so far been more reserved,” suggesting uncertainty about how far these projects will go.

Beyond energy, Iran has promised land allocation by March for the Rasht–Astara railway—a key link in the Russia-to-India North–South Corridor. Russian gas deliveries via Azerbaijan are also expected to begin soon. Several Russian firms are preparing to enter the Iranian market, reportedly under “special conditions,” Smagin wrote.

Yet while Iran’s dependence on Moscow is growing, Russia’s strategic interest in Tehran is more limited.

“Russia is now producing Iranian drones itself… with components largely of Russian or Chinese origin,” Smagin wrote, diminishing Iran’s role as a military partner. Trade between the two countries remains modest at around $5bn—dwarfed by Russia’s $50bn trade with Turkey, $11bn with the UAE, and $9bn with Egypt.

“Iran is no longer a top priority,” Smagin concluded. But as sanctions, economic instability and fear of renewed conflict deepen Iran’s isolation, Tehran is left with few alternatives. “Russia remains one of the few available sources” of investment and strategic cooperation.