Tehran’s Possible New Enrichment Plant

While the White House remains preoccupied with Gaza, Iran is moving toward completion of a brand-new nuclear facility 100 meters below ground, where it could enrich uranium to weapons-grade with immunity from U.S. airstrikes. The facility may not become operational this year, providing time for the United States and partners to pressure Tehran into disclosing its intentions — or to prepare military plans to prevent Iran from using the site for a breakout to nuclear weapons.

Since 2022, Iran has been building the deeply buried nuclear facility in mountains known as Kūh-e Kolang Gaz Lā, or “Pickaxe Mountain,” near the existing Natanz nuclear site. Tehran claims that it is building the facility to replace a damaged centrifuge assembly plant that was the target of sabotage in 2020. Yet Western intelligence officials fear the site could house a new uranium enrichment facility. The International Atomic Energy Agency (IAEA) has not yet reported a visit to the site.

The site may be more than 100 meters below the surface — deeper than the Fordow enrichment facility, which is 80 to 90 meters below ground. This could render the new facility impervious to even the largest U.S. bunker-buster bombs, which can reach depths of at least 60 meters.

Moreover, Iran may be violating its legal obligation to disclose information about the facility to the IAEA. The IAEA has repeatedly raised concerns that since 2021, Tehran has refused to implement a legal safeguards obligation known as “Modified Code 3.1.” This obligation is part of subsidiary arrangements to Iran’s IAEA comprehensive safeguards agreement (CSA), itself a legal requirement for all parties to the Nuclear Non-Proliferation Treaty.

Modified Code 3.1 requires states to declare the construction of new nuclear facilities and provide design information to the IAEA as soon as a decision is taken to construct them. The IAEA reported this year that Iran violated its safeguards agreement when it broke ground on a new nuclear reactor without notifying the IAEA or fulfilling its safeguards obligations. The IAEA also noted with concern that Tehran has announced plans to construct a research reactor and four other nuclear power plants.

Tehran claims to adhere to a previous version of Code 3.1, which requires it to notify the IAEA about nuclear facilities only six months before the introduction of nuclear material — or essentially just before they become operational. However, the IAEA requires time to design appropriate safeguards for nuclear material-producing facilities so that it can detect and prevent diversion to a military nuclear effort. This is why Modified Code 3.1 becomes an irreversible legal obligation once a state has acceded to it, as Iran has.

A more worrisome prospect is that Iran may never declare the facility but will instead use it for a rapid breakout to nuclear weapons. For example, Tehran could divert its enriched uranium stockpiles to the facility and quickly enrich the material to weapons-grade. Even if Western powers intervene, they may not be able to stop a breakout at the facility via military strikes using existing capabilities.

A small enrichment facility housing several hundred advanced centrifuges is all Iran requires to conduct a breakout to nuclear weapons. As of May 2024, Tehran could produce enough weapons-grade uranium for up to 13 bombs and enough for one weapon within a week, meaning the West has no time to lose.

The 35-nation IAEA Board of Governors, which recently voted to censure Iran’s non-compliance with its nonproliferation obligations, specifically called on Iran to implement Modified Code 3.1. If Tehran fails to comply and disclose to the IAEA information about the facility, the board should vote to refer Iran’s case to the UN Security Council, where any party to the 2015 nuclear deal with Tehran could then trigger the “snapback” of all UN sanctions on Iran within 30 days.

The United States, Israel, and their partners must simultaneously prepare military plans to damage the facility and stop an Iranian breakout. A nuclear weapons capability would provide cover for the regime to increase its destabilizing activities.

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