New Activity at Iranian Nuclear Site Shows Determination To Rebuild Program

The United States and Israel may need to strike Iran again to keep nuclear weapons out of Tehran’s grasp. Construction is nearing the final stages at a former nuclear weapons site destroyed by Israel in October 2024, according to new satellite imagery. While the intended use of the rebuilt site remains unclear, Iran previously used the site — known as Taleghan 2 within the Parchin military complex — to conduct experiments relevant to nuclear weapons. Israel’s strike reportedly disrupted this work. The United States and Israel damaged or destroyed numerous other Iranian nuclear sites with air strikes in June 2025.

The new construction at Taleghan 2, along with Iran’s activities over the past two months at other current and former nuclear sites, underscores that Tehran intends to rebuild its program despite the 12 days of airstrikes that took place in June.

Building Nearing Completion at Taleghan 2

On January 6, the Institute for Science and International Security published new imagery of ongoing construction at Taleghan 2. Based on images dated December 25 — along with earlier imagery — Iran is reconstructing a large cylindrical chamber, which is likely a high explosives containment vessel. That would replace a similar structure destroyed by Israel. Prior to 2004, Iran used the containment vessel and specialized equipment at Taleghan 2 for nuclear weapons experiments, specifically related to preparing the center of the core of Iran’s nuclear weapon design, known as a neutron initiator. It began to limit such work following international discovery of its illicit nuclear activities in 2002. U.S. and Israeli intelligence reportedly observed renewed Iranian work at the site in 2023, this time related to manufacturing plastic explosives used in nuclear detonations, prompting the October 2024 Israeli strike. 

Tehran is now hardening the structure with a concrete sarcophagus to protect against future strikes. The institute assesses that Iran restarted construction around May 2025 and that it is nearing completion. However, it is not certain the site will be used for nuclear weapons development, as containment vessels can also serve in the development of conventional weapons systems.

Construction and Excavation Proceed at Additional Nuclear Sites

Iran is also conducting excavation work at the Natanz Pilot Fuel Enrichment Plant, destroyed by the United States and Israel in June. According to the institute and imagery dated December 13, the regime has erected a privacy cover over the bombed facility, likely to assess whether key assets — such as limited stocks of highly enriched uranium — survived the strikes.

The institute also reported in November 2025 that Tehran is fortifying and continuing construction on a deeply buried facility at Pickaxe Mountain near the Natanz complex — a site not targeted by Washington or Jerusalem. Western intelligence agencies worry that this site could host a secret enrichment plant even harder to destroy than the Fordow enrichment plant.

At the Esfahan tunnel complex, bombed by the United States (where Tehran was developing another enrichment plant and may have stored HEU), the regime has been clearing debris from and fortifying the tunnel entrances.

Additionally, the institute’s assessments indicate limited but ongoing activity at damaged or destroyed weaponization facilities, where Iran appears to be removing rubble and potentially salvaging equipment.

New Strikes May Be Necessary

Iran is pursuing limited but increasing efforts to determine if nuclear assets survived the U.S. and Israeli strikes, while advancing facilities that could, for the purposes of nuclear weaponization, facilitate high explosives tests or produce weapons-grade uranium from any remaining HEU stocks or imported materials.

Though Tehran likely remains far from reconstituting a functional nuclear weapons program, the United States and Israel must stay vigilant, monitoring Iran’s efforts closely and watching for any foreign assistance that could accelerate rebuilding.

Eventually, President Donald Trump and Prime Minister Benjamin Netanyahu may need to follow through on their threats to strike any resumption of Iranian nuclear activities.

Andrea Stricker is a research fellow and deputy director of the Nonproliferation Program at the Foundation for Defense of Democracies (FDD). For more analysis from the author and FDD, please subscribe HERE. Follow Andrea on X @StrickerNonpro. Follow FDD on X @FDD. FDD is a Washington, DC-based, nonpartisan research institute focused on national security and foreign policy.