Iran’s Islamic Revolutionary Guard Corps claimed this week it recovered more than 15 unexploded American weapons from strikes on its territory and transferred them to technical and research units for reverse engineering — including, according to Iranian state media, a fully intact GBU-57 bunker-buster bomb that failed to detonate during US strikes on Iran’s nuclear facilities.
The claim has not been independently verified or acknowledged by the US government. The IRGC’s Imam Sajjad Corps in Hormozgan province said the haul included heavy missiles and ordnance from recent US and Israeli strikes.
The GBU-57 Massive Ordnance Penetrator — the largest conventional bunker-busting bomb in the US arsenal, weighing approximately 30,000 pounds — is designed to destroy deeply buried targets such as underground nuclear facilities.
Iranian state broadcaster PressTV reported separately on April 26 that IRGC units had neutralized or destroyed more than 60 missiles and drones in Hormozgan province and recovered more than 9,500 bomblets in Zanjan since the start of the conflict.
The weapons stem from Operation Midnight Hammer on the evening of June 21, 2025, when B-2 stealth bombers struck Iran’s Natanz, Fordow, and Isfahan nuclear sites and submarines launched more than 30 Tomahawk cruise missiles against surface infrastructure at Isfahan.
The possibility of unexploded ordnance at those sites emerged in February 2026, when Foreign Minister Abbas Araghchi told the IAEA that unexploded American bombs were present and that inspections could not proceed until security protocols were agreed. The IAEA confirmed that no existing framework governs inspections at bombed nuclear sites.
The precedent that concerns analysts most is the RQ-170. Iran recovered a largely intact US RQ-170 Sentinel stealth drone in 2011, produced a working copy within three years, and later developed armed combat variants. CENTCOM released a video of one such clone destroyed by a US airstrike on April 2, 2026.
Defense analysts say Iran cannot fully replicate the GBU-57 because it lacks the B-2, the only aircraft capable of delivering it. Studying its casing, fuse mechanism, and guidance architecture could, however, allow Iranian engineers to upgrade domestic penetrating warheads.
A December 2025 Tehran Times report said engineers had already developed a GBU-57-inspired warhead for the Fattah hypersonic missile capable of penetrating up to 20 meters of reinforced concrete, compared to approximately 60 meters for the US version.
The Tomahawk raises separate concerns as Iran already fields similar cruise missiles, and access to its terrain-following navigation and guidance systems could improve the accuracy and jamming-resistance of Iran’s existing arsenal.
US and Israeli officials have also flagged the risk that technical insights could be shared with Russia or China.
Washington has not responded publicly to the latest IRGC announcement. The War Zone reported in February that the Air Force had issued a sole-source contract to Boeing to replenish GBU-57 stocks expended in Operation Midnight Hammer, and that the Pentagon was separately reverse-engineering bomb components using ATACMS technology to address vendor dependency. A successor weapon, the Next Generation Penetrator, is also in development.
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