Iran’s Fordow hit by US bunker buster bombs: What you need to know about the secret nuclear site

The United States has struck Iran’s deeply fortified Fordow nuclear site, marking a dramatic escalation in efforts to dismantle Tehran’s nuclear capabilities. The overnight airstrike on June 21, part of Operation Midnight Hammer, was carried out using B-2 stealth bombers armed with 30,000-pound bunker-buster bombs—making it the first known US attempt to penetrate the underground facility near Qom. The move comes after days of Israeli bombardment that failed to significantly damage Fordow, a site central to Iran’s uranium enrichment program and long considered beyond the reach of conventional weapons.

Here are key facts about Iran’s Fordow nuclear facility:

Iran’s Fordow Fuel Enrichment Plant is one of the most heavily fortified and controversial sites in the country’s nuclear infrastructure. Located about 100 kilometers southwest of Tehran near the holy city of Qom, Fordow is buried deep within a mountain — up to 300 feet underground — and is designed to be shielded from conventional airstrikes.

Originally constructed in secret around 2006 and officially revealed by Iran in 2009, the site is operated by Iran’s Atomic Energy Organization and plays a central role in uranium enrichment. It is one of two facilities — alongside Natanz — where uranium has been enriched to levels close to weapons-grade.

Why Fordow matters

Fordow’s significance lies in both its output and its protection. The facility has been used to enrich uranium up to 60% purity — just a short step from the 90% enrichment level needed to produce nuclear weapons. In 2023, the International Atomic Energy Agency (IAEA) detected particles enriched to 83.7% purity at the site — the highest level ever publicly recorded in Iran.

This brought heightened international scrutiny, especially from Israel, which considers any Iranian move toward weapons-grade material an existential threat. Fordow’s fortified location makes it nearly invulnerable to Israeli munitions. Only the United States possesses the 30,000-pound GBU-57 Massive Ordnance Penetrator — a “bunker buster” capable of reaching its underground centrifuge halls.

The strikes on Fordow

In the early hours of Saturday night (June 21), the United States launched a military operation — Operation Midnight Hammer — targeting Fordow, Natanz, and Isfahan. US President Donald Trump authorised the use of B-2 stealth bombers equipped with GBU-57 bombs to strike Fordow’s underground halls.

“We devastated the Iranian nuclear program,” said US Defense Secretary Pete Hegseth after the strikes. “This operation was about neutralizing threats — not regime change.”

Satellite images reveal surface damage

According to satellite imagery and initial Pentagon assessments, the attacks caused visible damage around the facility, including craters and collapsed tunnel entrances.

However, the IAEA has reported no increase in off-site radiation levels, and a full damage assessment is still underway.

Radiation risk and monitoring challenges

The IAEA confirmed that no elevated radiation levels have been detected following the strike. But experts caution that radiation and chemical contamination inside the site are likely, and monitoring efforts have become more difficult.

Due to the destruction of infrastructure and dispersal of materials, traditional environmental sampling techniques — essential for detecting illicit nuclear activity — may now be unusable at the site.

Strategic implications

The Fordow strike was viewed as a turning point in the conflict. Israeli airstrikes over the past week had failed to significantly damage Fordow due to its depth and air defenses. By stepping in with bunker busters, the US delivered what many analysts view as a critical blow to Iran’s nuclear capabilities.

Still, experts warn that much of Iran’s enriched uranium stockpile may have already been moved to undisclosed hardened sites, complicating efforts to track and contain its nuclear ambitions.