Did the most advanced bunker-busting bombs of the United States finally defeat Iran’s engineering marvels of below-ground nuclear bases? The legacy of Operation Midnight Hammer is a case study on the constraints of military technology, the resiliency of nuclear infrastructure, and the continued sophistication of nuclear diplomacy.
The strikes, launched on June 21, 2025, targeted Iran’s top three nuclear facilities Fordow, Natanz, and Isfahan by a combination of seven B-2 Spirit planes, 14 GBU-57 Massive Ordnance Penetrators, and over two dozen Tomahawk cruise missiles. As detailed at the Pentagon by Joint Chiefs of Staff Chairman General Dan Caine, the attack was “years in the making,” with the GBU-57 crafted to counter the threat posed by Fordow, a “mountain-built” site and “critical element” of Iran’s covert nuclear weapons program.
The technological prowess of the GBU-57 cannot be doubted. It has a weight of 30,000 pounds and can penetrate 200 feet of earth or 60 feet of reinforced concrete. It is the sole non-nuclear weapon in the American inventory that can strike facilities like Fordow. Twelve MOPs were dropped on Fordow during the operation with specially configured fuse settings to maximize penetration and internal blast effect. According to Caine, the “primary kill mechanism” was a combination of overpressure and blast meant to destroy centrifuge arrays and tunnel facilities deep within the mountain. Iran’s nuclear facilities’ engineering, however, was robust.
Fordow’s halls for enrichment are believed to be buried beneath 45–90 meters of rock, and tunnel entrances are capped with rock and sand in the days before the attack. Satellite imagery assessed by independent experts showed altered topography and fresh craters, but internal damage cannot be assessed. IAEA Director General Rafael Grossi stated that “the degree of damage inside the uranium enrichment halls can’t be determined with certainty”. At Natanz, already badly harmed by prior Israeli strikes, the U.S. used ground-penetrating bombs, but Iran is said to have begun constructing even deeper tunnels, possibly outside the limits of the GBU-57.
Isfahan, struck with Tomahawk missiles, saw extensive destruction to above-ground infrastructure, including the only metal conversion plant that Iran needed for nuclear enrichment a strike that CIA Director John Ratcliffe told lawmakers would take “years to rebuild.” The subterranean storage facilities at Isfahan are too deep to be targeted by even the MOP, so the U.S. targeted tunnel entrances. Despite these efforts, the latest U.S. assessment concludes that only Fordow was “mostly destroyed,” delaying operations there by as long as two years.
Natanz and Isfahan experienced less severe damage, and U.S. intelligence suggests Iran can resume enrichment in those sites within a matter of months if it chooses to do so. This stands in opposition to public pronouncements by President Trump and Pentagon spokesmen, who insisted that Iran’s nuclear program had been “completely and totally obliterated.” Resilience of the Iran program relies not only on material engineering but also on proliferation of key assets.
Iranian officials supposedly evacuated personnel and transferred stores of enriched uranium prior to the bombings, as witnessed by unusual truck traffic observed outside Fordow in advance. Iran’s location of 400 kilograms of 60 percent-enriched uranium is not known, raising grave issues of proliferation. Analysts are saying that, with crippled plants notwithstanding, the technical capability and remaining centrifuge stocks should permit Iran to reconstitute or shift its enrichment capacity with relative speed. Operation Midnight Hammer also demonstrated the shortcomings of military solutions to nuclear proliferation. The U.S. Central Command had a far more extensive, multi-week attack plan for other targets, but it was rejected due to concerns regarding casualties and the risk of escalation. As one senior official described, “It would be a protracted air campaign.”
The environmental impacts of the strikes were negligible. The IAEA and independent external nuclear specialists independently confirmed no significant release of radioactivity, as uranium enrichment plants are low-pressure and the involved materials are not short-term acutely toxic.
As policymakers weigh the implications, the strategic and technical messages are unmistakable: the intersection of advanced weapons and highly engineered nuclear facilities produces ambiguous consequences. The ability to defer, but not forestall, Iran’s nuclear capability underscores the continued need for robust verification, diplomatic engagement, and creative solutions to the proliferation issue.
