Defense News: US air force orders smaller, deadlier bunker buster bombs

US air force orders smaller, deadlier bunker buster bombs

ARA and Boeing to develop lighter, smarter munitions after Iran strike exposes limits of Massive Ordnance Penetrator (MOP).

By Anna Ahronheim, Jerusalem Post, September 14, 2025

https://www.jpost.com/defense-and-tech/article-867355

B-2 bomber drops a GBU-57 during a test  (photo credit: US AIR FORCE)

The US Air Force has awarded defense firm Applied Research Associates (ARA) and Boeing a two-year contract to design and prototype the next generation of bunker-busting bombs, designed to be smaller yet more lethal than the one that struck a key Iranian nuclear facility in June. 

 According to a statement by ARA, the company was awarded a 24-month contract by the Air Force Life Cycle Management Center, Eglin Munitions Directorate, to serve as the System Design Agent for the development of a prototype air-to-ground Next Generation Penetrator weapon system.

Boeing, which originally made the BGU-57 Massive Ordnance Penetrator (MOP), will team up with ARA for the new munition. ARA will lead design maturation, while Boeing will drive the tail kit development and support all-up round integration. ARA will also produce and test sub-scale and full-scale prototype munitions.

“This effort will evaluate capabilities against hard and deeply buried targets that pose critical challenges to US national security,” ARA said in a statement. The contract amount was not disclosed.

Lighter, More Versatile

In March 2024, the Air Force issued a request for information from industry for a Next-Generation Penetrator (NGP), seeking concepts for “a prototype penetrator warhead design capable of defeating Hard and Deeply Buried Targets.” 

The U.S. Air Force B-2 bomber ''Spirit of Oklahoma'' is refueled in-flight over Eastern Washington state, April, 27, 2002 while participating in ''Northern Edge,'' Alaska's largest annual joint training exercise. (credit: REUTERS/JEFF T. GREEN)

The RFI specified that the prototype design should not exceed 22,000 pounds and be capable of blast/fragmentation/and penetration effects. A lighter more versatile munition would allow it to be used from a wider range of platforms, including long-range strike aircraft,  potentially allowing deployment from a wider range of aircraft including the upcoming B-21 Raider stealth bomber. 

Currently, only the B-2 bomber is the only aircraft able to carry a munition like the MOP, and only two per sortie.

The RFI also required that the navigation system be capable of operating in a GPS-degraded or denied environment. It also called for 10 subscales and 3-5 full-scale warhead prototypes ready within 18-24 months from the contract award.  

The Legacy of the MOP

Developed in the early 2000s by Boeing and the Defense Threat Reduction Agency (DTRA), the GBU-57 MOP was designed to neutralize Hard and Deeply Buried Targets (HDBTs) — including underground labs, command centers, and chemical, biological, and nuclear facilities. 

 An Air Force fact sheet described the MOP as “a weapon system designed to accomplish a difficult, complicated mission of reaching and destroying our adversaries’ weapons of mass destruction located in well-protected facilities.”

Weighing 30,000 pounds (warhead alone weighing 5,740 pounds) and measuring over 20 feet long, the MOP can penetrate up to 200 feet of earth or 60 feet of reinforced concrete, making it the most powerful non-nuclear bomb in the US arsenal.

According to a report in Scientific American, the kinetic strike “delivers 800 to 900 megajoules (about 758,000 to 853,000 British thermal units) of kinetic energy—comparable to a 285-ton Boeing 747-400 touching down at 170 mph or a 565-ton Amtrak Acela train moving at 120 mph.”

Why the Upgrade?

With a reduced weight and enhanced guidance systems, including GPS-denied navigation and advanced fuzing capable of detecting underground voids, the new penetrator aims for greater flexibility and precision. 

The announcement of the contract award comes in the wake of Operation Midnight Hammer, the first-ever combat use of the MOP, which targeted Iran’s deeply buried nuclear facilities in June 2025. During the operation, seven B-2 Spirit bombers dropped 14 GBU-57s on sites in Fordow, Natanz, and Isfahan, locations long suspected of housing critical components of Iran’s nuclear program.

While US officials hailed the mission as a success, independent assessments suggested mixed results. Fordow reportedly suffered severe damage, but Natanz and Isfahan may recover more quickly than anticipated. 

The operation highlighted both the strengths and limitations of the MOP, particularly its massive size, limited aircraft compatibility, the challenge of penetrating ultra-hardened targets, and the continued development of sophisticated defenses.

US Wants Smaller Bunker-Buster Bomb | Pentagon Pushes Next-Gen Penetrator, B-21 Integration 

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