Nuclear Expansion: $25 Billion Sirik Plant Deepens Russian-Iranian Ties

International oversight of Iran’s nuclear program has weakened just as Moscow and Tehran finalized a new agreement for a major power facility. The deal locks in long-term dependencies on Russian technology and fuel while inspectors struggle to verify activities at sensitive Iranian sites.

In September 2025, Russia and Iran signed an agreement to construct the Sirik nuclear power plant in Hormozgan Province, near the Strait of Hormuz. Iran’s state news agency IRNA reported the deal is valued at $25 billion. The facility is designed with a combined capacity of approximately 5 gigawatts. By comparison, the completed Bushehr complex on Iran’s southern coast will have a capacity of under 3 gigawatts.

Rosatom, Russia’s state nuclear corporation, continues operations at the existing Bushehr plant. Following the start of the US-Iran war in February, Rosatom evacuated most of its workforce. By October 11, the agency reported that 135 engineering and technical specialists had returned to the site. Construction on a second reactor unit at Bushehr is more than 60 percent complete, with a target operational date of 2029. Work on a third unit is also under way.

The partnership rests on the Comprehensive Strategic Partnership Treaty, which entered into force in October 2025, and the Inter-governmental Cooperation Plan for 2024-2026. Nikita Smagin, an analyst at the Carnegie Endowment for International Peace, noted in a November 2025 article that the balance in the relationship is shifting in Russia’s favor. He wrote that Iran is in dire need of investment and that Russia remains one of the few available sources. Dmitry Kovchegin and Arkady Mil-Man of Israel’s Institute for National Security Studies described Moscow’s policy as a calculated balancing strategy aimed at improving relations with the United States.

The International Atomic Energy Agency reported on June 4 that it conducted an inspection at Bushehr from June 1 to 3. During that reporting period, the agency was unable to inspect four declared uranium enrichment facilities. The IAEA could not verify the status of nuclear material at those sites or confirm whether Iran suspended enrichment, reprocessing, or heavy-water activities required by UN Security Council resolutions.

Russia faces extensive Western sanctions following its 2022 invasion of Ukraine, while Iran has faced decades of restrictions over its nuclear program and military activities. The Arms Control Association stated in June 2025 that Iran’s accumulation of uranium enriched to 60 percent has no civil justification. The group noted that this level of enrichment puts Iran in a better position to quickly produce weapons-grade material.

The new Sirik plant will further tie Iran’s civilian nuclear sector to Russian infrastructure. The agreement expands cooperation beyond Bushehr, which has been the centerpiece of the relationship since its first reactor began commercial generation in 2013.