OSINT Suggests US B-1B Bombers Using GBU-72 Bunker-Busters on Hardened Iranian Ammo Sites.

U.S. Air Force B-1B bombers are conducting strikes on hardened targets in Iran as part of Operation Epic Fury, with the Pentagon confirming bomber involvement but not disclosing the weapons used. Analysis of strike footage circulated by open-source intelligence accounts suggests the possible use of the 5,000 lb class GBU-72 Advanced Penetrator, designed to destroy deeply buried and reinforced facilities.

If accurate, the use of deep-penetration munitions would mark a shift in Epic Fury toward targeting fortified ammunition depots and underground storage networks rather than surface infrastructure. Such a move would expand the operation’s scope and signal the capability to penetrate Iran’s most protected military assets while maintaining pressure across multiple hardened sites.

Read also: U.S. Deploys B-1B Lancer Bombers to UK Ahead of Possible Large-Scale Strikes on Iran

A U.S. Air Force B-1B Lancer operates in support of CENTCOM’s Operation Epic Fury, March 2026. Open-source intelligence analysis of circulating footage suggests the possible use of bunker-buster munitions in strikes against hardened targets, although this remains unconfirmed. (U.S. Air Force photo)

According to U.S. Central Command statements released in March 2026, Operation Epic Fury involves coordinated strikes against Iranian missile infrastructure, command-and-control nodes, and military facilities. The confirmed deployment of B-1B bombers highlights a deliberate operational approach combining long-range strike aviation with penetrator-class munitions to degrade hardened underground networks central to Iran’s military resilience and deterrence posture.

The B-1B Lancer is a supersonic heavy bomber optimized for conventional warfare, capable of carrying more than 75,000 lb (≈34,000 kg) of mixed ordnance across three internal weapons bays. Originally developed as a nuclear-capable platform, it has been fully transitioned to conventional missions and now serves as a cornerstone of U.S. long-range strike capability. Its mission set includes deep-strike interdiction, close air support, maritime strike, and suppression of enemy infrastructure, and it can engage multiple targets in a single sortie.

In high-intensity operations such as Operation Epic Fury, the B-1B is typically employed after stealth assets have suppressed enemy air defenses. Once airspace access is established, the aircraft delivers large volumes of precision-guided munitions against distributed and hardened targets. This approach enables sustained pressure on critical infrastructure while maximizing sortie efficiency and reducing reliance on limited stealth-bomber availability.

The GBU-72 Advanced 5K Penetrator represents a new generation of bunker-busting munitions designed to defeat deeply buried and reinforced targets. Weighing approximately 5,000 lb (≈2,268 kg), the weapon combines GPS guidance with a hardened steel casing and a delayed fuze mechanism, enabling it to penetrate layers of concrete, rock, and soil before detonating within the target. This internal explosion significantly increases destructive effectiveness against underground facilities compared to surface-detonating munitions.

Compared to the GBU-31(V)3/B with BLU-109 warheads, the GBU-72 provides greater penetration against thicker structures while remaining lighter and more flexible than the 30,000 lb (≈13,600 kg) GBU-57. This makes the GBU-72 a critical intermediate solution that combines deployability with increased lethality.

Additional insight into the operational integration of the GBU-72 was provided on September 2, 2023, when the U.S. Department of Defense reported that Airmen from the 57th Munitions Squadron and the 57th Weapons Squadron conducted training to assemble and load the weapon. This training reflects the growing importance of penetrator-class munitions in modern conflict environments, where adversaries increasingly rely on underground infrastructure to ensure survivability.

Analysis of the circulating footage has focused on several indicators consistent with the use of penetrator weapons. Observers have noted limited surface blast effects, delayed detonation signatures, and impact characteristics suggesting deep penetration prior to explosion. While these assessments remain unverified, they align with known employment profiles of the GBU-72 when used against buried ammunition depots or reinforced storage facilities.

Iran has invested extensively in hardened and underground military infrastructure, including ammunition depots and ballistic missile storage complexes often embedded in mountainous terrain or protected by reinforced concrete layers. These facilities are designed to withstand conventional airstrikes and preserve operational capability under sustained attack, forming a critical component of Iran’s defensive and deterrent strategy.

Targeting such ammunition depots carries direct operational consequences. Their destruction can disrupt missile reload cycles, reduce sustained launch capacity, and trigger secondary explosions that amplify damage within storage networks. This not only degrades immediate combat capability but also affects longer-term operational endurance by limiting access to stored munitions.

The integration of B-1B bombers and advanced penetrator munitions in Operation Epic Fury shows a structured U.S. strategy to systematically degrade hardened military infrastructure. High-payload platforms and precision-guided penetrators enable U.S. forces to more effectively threaten deeply buried targets.

While the specific strike remains unconfirmed, the operational effect is clear: the capability to accurately destroy hardened underground targets reinforces U.S. deep-strike capacity and enhances deterrence against adversaries reliant on similar infrastructure.

Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.