First Combat Confirmation: GBU-72 Employed Against Iranian Hardened Targets

On 18 March 2026, United States Central Command (CENTCOM) confirmed the first operational employment of the GBU-72 Advanced 5K Penetrator in combat operations. Target: hardened and deeply buried anti-ship cruise missile (ASHCM) facilities operated by the Islamic Republic of Iran’s Islamic Revolutionary Guard Corps Navy (IRGCN) and Aerospace Force (IRGCAF) near the Strait of Hormuz and the Persian Gulf.

The GBU-72 belongs to the family of precision-guided bunker-busting munitions that bridge the performance gap between unguided conventional penetrators and strategic deep-strike weapons. This first operational employment represents five years of development, testing, and military qualification since the programme inception in 2021.

The Iranian targets struck were underground silos housing Noor, Qader, and Abu Mahdi family anti-ship cruise missiles. The IRGCN operates an estimated fleet of 2,500–3,000 such missiles across distributed coastal defence positions. Hardened deeply buried targets (HDBTs) of this class have historically required either sustained conventional bombing or strategic-class bunker-busters to achieve neutralisation. The GBU-72 represents a precision-guided step between these extremes.

Technical Specification: The GBU-72 Architecture

Guidance and Navigation

The GBU-72 uses the Boeing Tail Kit Assembly (TKA), the standard JDAM retrofit applied to existing general-purpose bombs from 500 lb to 5,000 lb classes. GPS provides primary guidance; an inertial measurement unit (IMU) provides backup in GPS-denied environments. Typical circular error probability (CEP) is approximately 3–5 metres under GPS conditions. Navigation updates during flight allow mid-course correction if ground-station guidance is available, though in contested airspace this may not be reliable.

Warhead Architecture and Penetration Physics

The GBU-72 warhead body consists of hardened steel casing designed to withstand massive deceleration loads as the munition penetrates earth and concrete. Internal shock absorbers protect the fuze and explosive fill during impact. Upon penetration, delayed fuzing allows detonation to occur after the warhead has burrowed to maximum depth, maximising the containment effect and concentrating blast energy within the target structure rather than venting to atmosphere.

Concrete penetration depth of 22 feet (6.7 metres) at typical impact angles puts it in the class of specialist bunker-busters, though below the penetration depth of much heavier weapons like the BLU-109 warhead (employed with the GBU-28 Bunker Buster) which achieves approximately 80 feet of concrete penetration. The GBU-72 represents a high-precision, lower-collateral-damage alternative to the strategic-class penetrators.

Operational Deployment and Delivery Platforms

Delivery Platforms Confirmed: General Dynamics F-15E Strike Eagle (US Air Force) and Rockwell B-1B Lancer (USAF). Both platforms have hardened bomb racks compatible with the 5,000 lb class warhead and possess sufficient range and payload capacity to deliver GBU-72 weapons from forward operating bases in the region or from continental United States (CONUS) sorties via aerial refuelling.

The F-15E Strike Eagle typically carries two GBU-72 weapons in its internal and external hardpoints, depending on fuel load and standoff range requirements. The B-1B Lancer can carry multiple weapons of this class internally, making it suitable for sustained campaign operations.

Combat Effectiveness Assessment: Iranian Target Damage

CENTCOM reported that tunnels and surface structures at Hajiabad and associated coastal defence installations sustained direct penetrator strikes. However, Iranian military official statements acknowledged that “some silos remained operational” post-strike. Open-source imagery analysis published on 22 March 2026 by specialist defence forums suggests that while surface installations were damaged, underground silo structures remained largely intact. This assessment carries moderate confidence: deep underground structures are inherently difficult to assess via overhead imagery alone.

The discrepancy between CENTCOM claims of successful strikes and Iranian assertions of operational continuity raises an important technical question: the GBU-72’s penetration depth of 22 feet (6.7 m) of reinforced concrete, while formidable for conventional penetrators, may be insufficient to reach the deepest levels of ultra-hardened Iranian ASHCM silos, which are understood to extend 30–40+ metres underground with multiple hardened compartments.

Historical Context: Development and Testing Programme

The GBU-72 Advanced 5K Penetrator programme began formal development in 2017, emerging from Air Force Studies, Analyses, and Assessments (AFAA) recognition that the existing inventory of bunker-buster munitions was imbalanced: strategic-class weapons (GBU-28) were politically and operationally expensive to employ; smaller precision penetrators lacked sufficient warhead energy to defeat modern hardened structures.

Operational testing at Eglin Air Force Base from 2018 to 2021 focused on concrete penetration performance, fuze reliability, and accuracy under GPS-denied conditions. The munition received military specification (MIL-SPEC) approval for operational deployment in October 2021. Limited inventory production followed throughout 2022–2024, with GBU-72 weapons only gradually entering squadron-level training and readiness rotations.

This first combat employment, therefore, represents both capability maturation and operational urgency. The selection of the GBU-72 for strikes against Iranian ASHCM positions signals that US Central Command assessed these targets as requiring precision penetration but at a cost and collateral-damage profile more acceptable than strategic-class alternatives.

WOME Technical Implications

Data Gaps and Confidence Assessment

Open-source reporting provides confirmation of the GBU-72’s first combat deployment and general technical specifications, but several operationally significant details remain unconfirmed. Exact NEQ and explosive fill composition are not disclosed in any published sources examined. The precise number of GBU-72 weapons deployed in Operation Epic Fury is unknown; CENTCOM released no sortie counts or weapon loads. Post-strike battle damage assessment remains contested: CENTCOM claims successful target neutralisation; Iranian military asserts operational continuity. Overhead imagery is inconclusive at classification levels available to open-source analysts.

Most critically, long-term combat effectiveness against ultra-hardened Iranian ASHCM silos cannot be independently verified without access to classified intelligence assessments or high-resolution imagery analysis protocols not available to open-source researchers.

Overall Confidence: MEDIUM. CENTCOM’s formal confirmation of GBU-72 employment (HIGH confidence). Technical specifications from published sources (MEDIUM confidence — precise NEQ estimated but not official). Combat effectiveness assessment (LOW confidence — contested claims, insufficient imagery).