- Iran and Russia formalize a 20-year strategic partnership treaty in 2025, expanding military-technical cooperation without a mutual defense clause.
- Iran receives Russian Su-35 fighter jets, with deliveries of up to 48 units expected to bolster air defenses starting in 2026, reciprocating Iran's drone supplies to Russia for use in Ukraine.
- Western sanctions drive de-dollarization efforts and BRICS coordination, with Russia advancing a $25 billion Rosatom deal for four new nuclear reactors in Iran.
A Strategic Shift in Military Ties
Recent developments highlight a significant deepening of Russia-Iran military-technical cooperation, moving beyond earlier speculation about secret missile deals to focus on tangible, high-profile agreements. In 2025, the two nations ratified a Comprehensive Strategic Partnership Treaty, formalizing a 20-year framework for collaboration across political, economic, security, and technological fields. This treaty, which lacks a mutual defense clause, has paved the way for expanded arms transfers and nuclear projects, according to diplomatic sources familiar with the negotiations.
Efforts to strengthen these ties have accelerated amid ongoing Western sanctions. In December 2025, foreign ministries from both countries signed a 2026-2028 consultations program following talks in Moscow, signaling a commitment to sustained engagement. The partnership builds on prior deals, such as the 2007 delivery of S-300 air defense systems and 2024 announcements regarding Su-35 fighter jets, but recent moves represent a more concerted push to counter external pressures.
Fighter Jets and Nuclear Ambitions
A key element of this cooperation is Iran's acquisition of Russian Su-35 fighter jets, with deals for up to 48 units expected to enhance its air defenses starting in 2026. This transfer reciprocates Iran's supply of over 38,000 drones to Russia for use in the Ukraine conflict, creating a symbiotic relationship that bolsters both nations' military capabilities. "The Su-35 deliveries are a game-changer for Iran's defensive posture," said an analyst who requested anonymity due to the sensitivity of the matter. "They provide advanced technology that could complicate potential strikes by Israel or the U.S."
Simultaneously, Russia is advancing a $25 billion Rosatom deal for four new nuclear reactors in Iran, part of broader energy and technology collaborations. This nuclear support was discussed in January 2025 talks between Russian President Vladimir Putin and Iranian President Masoud Pezeshkian, aiming to strengthen Iran's infrastructure against sanctions. The move has raised concerns among Western officials about nuclear escalation risks, with warnings against Russia sharing sensitive secrets that could aid Iran's missile programs.
Economic and Political Drivers
Western sanctions on both nations are driving de-dollarization efforts and increased coordination within BRICS, with expanded ties in energy, trade, transport, and space. A trilateral pact with China in January 2026 further bolsters economic resilience, creating a bloc that challenges traditional Western influence. Russia acts as an intermediary for Iran-Israel de-escalation messages, as seen in December 2025, despite Israeli concerns over Iran's ballistic missile reconstitution. Iran refuses concessions on its missile program, viewing it as a core deterrent, and has been rebuilding its capabilities with aid from China post a 2025 war with Israel.
Regional Gulf states worry about heightened security threats from these arms ties, potentially escalating tensions. No widespread public reactions have been reported, but analysts note Iran's "Axis of Resistance" and missiles as pillars of its defense strategy. The partnership dates back to earlier collaborations like 2000 Su-25 jets and 2005 nuclear fuel deals, but it has intensified post-Ukraine war through sanction evasion and military exchanges.
Looking ahead, Su-35 deliveries in 2026 and nuclear reactor builds could strengthen Iran's defenses, complicating regional dynamics. The 20-year treaty risks Gulf instability and nuclear proliferation in the long term, with experts predicting Russia will leverage Iran against the West. Iranian officials prioritize "hard power" for negotiations, as seen in ongoing U.S.-Iran nuclear talks that began in April 2025 but face hurdles from Iran's missile advancements and external aid. Attempts to reach Iranian and Russian representatives for comment on the latest developments were unsuccessful at the time of publication.