US strikes Iran missile sites with 5,000 pounds bunker buster bombs in Strait of Hormuz.

U.S. struck Iranian coastal missile facilities along the Strait of Hormuz with 5,000-pound bunker-buster bombs, demonstrating the capability of the U.S. Air Force to defeat deeply buried missile threats.

Conducted as part of the ongoing U.S.-Israeli campaign launched on February 28, the strikes targeted reinforced coastal sites using penetrator weapons such as the GBU-28 or GBU-72 deployed from aircraft such as F-15Es and B-1Bs. Announced by CENTCOM on March 17, the operation directly helped to secure a contested strategic chokepoint handling nearly 20% of global oil flows.

Related news: U.S. F-15E Strike Eagles Deploy GBU-31 Bunker-Buster Bombs Against Hardened Targets in Iran

The GBU-72 Advanced 5K Penetrator, built to be carried not only by heavy bombers but also by tactical aircraft such as the F-15E, became one of the three standard U.S. bunker buster bombs for striking buried infrastructure such as missile storage sites. (Picture source: US Air Force)

On March 17, 2026, the U.S. Central Command (CENTCOM) announced that U.S. forces struck Iranian missile facilities along the Strait of Hormuz using multiple 5,000-pound deep penetrator bombs, as these hardened coastal positions housing anti-ship cruise missiles threatened maritime traffic through a corridor handling close to one-fifth of global oil flows. The targeted sites, located along Iran’s coastline and designed to withstand conventional air attack, required weapons capable of penetrating reinforced structures or underground storage areas. The operation occurred during an ongoing U.S. and Israeli campaign initiated on February 28, following Iranian actions affecting access to the strait and regional shipping.

The current U.S. 5,000-lb penetrator inventory is limited to a small number of weapons designed specifically for such hardened and deeply buried targets. The GBU-72 Advanced 5K penetrator, entering service in 2021, uses a modern penetrator body with improved metallurgy and a GPS/INS guidance kit derived from JDAM architecture, enabling all-weather accuracy within a few meters. The GBU-28, developed in 1991, weighs close to 5,000 lb and contains about 630 lb of high explosive within a dense steel casing capable of penetrating more than 50 meters of earth or about 5 meters of reinforced concrete under optimal conditions. The GBU-37 provides a GPS-guided variant of the same penetrator body, extending capability to poor weather environments while retaining similar penetration physics.

These bombs are deployable from aircraft such as the F-15E and B-1B. The heavier 30,000-lb GBU-57 was not used in this case due to its requirement for B-2 or B-21 bombers and its role against targets buried significantly deeper than coastal missile installations. A bunker-buster is a bomb specifically engineered to penetrate hardened or buried targets before detonation, using kinetic energy and delayed fuzing rather than relying solely on explosive blast at the surface. The key advantage of such bombs is the ability to transfer energy through a dense penetrator body into the target structure, allowing the weapon to concentrate destructive force inside the structure before detonation occurs.

In contrast, conventional bombs typically detonate on impact or above ground, dispersing energy outward and limiting effectiveness against reinforced or underground facilities. The construction of a bunker buster bomb includes high-density steel casings designed to withstand impact without deformation, as well as guidance systems that enable precise targeting. Modern variants use GPS and inertial navigation, while delayed-action fuzes are calibrated to detonate after a specific penetration depth or upon detecting a void within the structure. These weapons date back to World War II with the development of British “earthquake bombs” such as the Tallboy and the Grand Slam, which weighed several tons and were designed to generate shockwaves capable of collapsing reinforced structures.

These bombs achieved high velocities through aerodynamic shaping and were constructed with hardened steel casings to survive impact with the ground. Rather than directly penetrating targets, they were intended to detonate beneath or near structures, to compromise heavily reinforced installations such as U-boat pens with concrete thickness exceeding four meters. However, the lack of precise guidance required specific release conditions and limited their effectiveness against smaller or deeply buried targets. Their reliance on shockwave propagation rather than controlled penetration also reduced predictability in certain operational scenarios. These limitations led to further development of weapons capable of direct penetration and controlled detonation.

The transition from shockwave-based destruction to kinetic penetration marked a shift toward more predictable and targeted effects. The evolution toward modern bunker-busters accelerated during the 1991 Gulf War, when existing munitions proved insufficient against deeply buried Iraqi command centers. The GBU-28 was then rapidly constructed using modified 8-inch artillery barrels as penetrator casings, producing a dense, elongated body capable of high penetration depth. It was deployed within weeks of development and demonstrated the ability to penetrate reinforced concrete structures before detonation, achieving effects not possible with earlier bombs.

The integration of laser guidance enabled precise targeting of specific bunkers, reducing the number of weapons required to achieve destruction. Subsequent upgrades introduced improved steel alloys and explosives, as well as GPS and inertial navigation systems that removed dependence on visual designation. This transition also led to the diversification of the bunker busters based on weight and penetration capability, including 2,000-lb, 5,000-lb, and 30,000-lb bombs. Upon impact, the weapon’s mass and velocity generate sufficient kinetic energy to penetrate layers of soil, rock, or reinforced concrete, with the hardened casing preventing structural failure of the munition.

After penetration, a delayed fuze triggers detonation, ensuring that the explosion occurs within or beneath the target, producing confined blast effects and high-pressure shock within the structure, increasing the likelihood of collapse or functional destruction. Advanced fuzes can adjust detonation timing based on impact conditions or detect transitions between solid material and voids. In current operations, bunker buster bombs are used to target missile launch systems, underground storage facilities, and fortified command structures that are designed to resist conventional strikes, making them relevant in the 2026 Iran war, as this state possesses multiple hardened military infrastructures.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.