Russia and Iran are broadening their nuclear partnership at a time when both face Western sanctions and international isolation. The cooperation covers the building of nuclear power plants, the supply of fuel and wider technological collaboration, and it is raising questions about how well international agencies can monitor Iran's atomic activities.
The centerpiece remains Bushehr, Iran's first operating nuclear power station, on the country's southern coast. Russia's state nuclear corporation, Rosatom, signed a contract to complete the first reactor in 1995, but the unit did not reach full commercial electricity generation until 2013. Rosatom has kept working there despite the military escalation in the region. After the US-Iran war began in February, it pulled most of its workers out of Iran, but many have returned. By October 11, the company reported that 135 engineering and technical specialists were back on site.
Construction is continuing on two further reactor units at Bushehr. According to Rosatom, work on the second unit is more than 60 percent complete, with operations targeted to start in 2029, and the third unit is also under construction.
The legal basis for the relationship is the Comprehensive Strategic Partnership Treaty, which formally entered into force in October 2025. The practical road map is the intergovernmental Cooperation Plan for 2024 to 2026, approved in September 2024. For Russia, the partnership offers commercial opportunities and a way to keep influence in the Middle East. For Iran, it provides access to nuclear technology, expertise and fuel.
The gains are not evenly shared, analysts say. Writing for the Carnegie Endowment for International Peace in November 2025, Nikita Smagin said "the balance in the relationship is once again shifting in Russia's favor." He noted that Iran urgently needs investment and that "Russia remains one of the few available sources." Researchers at Israel's Institute for National Security Studies described Moscow's approach as a "calculated balancing strategy" that combines condemnation of escalation, limited assistance, mediation offers and efforts to improve ties with the United States.
The partnership extends beyond Bushehr. In September 2025, the two countries signed an agreement to build a new plant, Sirik, in Hormozgan Province near the Strait of Hormuz. Iran's state news agency IRNA reported that the deal was worth $25 billion and that the units would have a combined capacity of about 5 gigawatts, compared with under 3 gigawatts for the completed Bushehr complex. If finished, Sirik would tie Iran's civilian nuclear sector to Russian technology and fuel for decades.
Wider links have also grown. A 2025 analysis by the Center for Naval Analyses found that military contacts, arms transfers and technical cooperation between the two countries have expanded since Russia's 2022 invasion of Ukraine. They have also pursued trade agreements and closer banking ties, though the researchers said economic competition between them could limit long-term growth.
Meanwhile, the International Atomic Energy Agency faces serious obstacles in Iran. In a report published June 4, it said it inspected Bushehr from June 1 to 3 but could not carry out inspections at other declared sites during the reporting period, including four uranium enrichment facilities. It also could not verify nuclear material at those sites or confirm whether Iran had suspended enrichment, spent fuel reprocessing and heavy-water-related activities. The report describes that period and is not a real-time picture of current access.
Nonproliferation specialists have voiced concern about transparency and possible diversion of sensitive technology. Some analysts point to Iran's stockpile of uranium enriched to 60 percent. That is not weapons-grade, but it can be enriched to around 90 percent. The Arms Control Association said in June 2025 that such enrichment "has no civil justification and puts Iran in a better position to quickly produce enough weapons-grade material for a bomb."
