The United States Air Force is stepping up its game in the world of bunker-busting weaponry, signaling a new era in military technology aimed at countering the ever-evolving threats posed by adversaries with deeply buried and fortified facilities. The move follows the high-profile use of the 30,000-pound GBU-57 Massive Ordnance Penetrator (MOP) during Operation Midnight Hammer, a secretive mission in June 2025 that targeted Iran’s nuclear sites at Natanz and Fordow. According to Business Insider, the operation marked the first time the MOP was deployed in combat, with seven B-2 Spirit stealth bombers dropping a total of 14 bombs to devastating effect. Intelligence reports indicated that the deeply buried facilities were destroyed, with photographs showing clusters of neat holes on the surface—evidence of the MOP’s brute force.
Yet, as the dust settled, it became clear that the Pentagon’s current bunker-busting arsenal, while formidable, may not be enough for the hardest targets. As Popular Mechanics reports, adversaries like North Korea and China are pushing the boundaries of underground construction, with command centers and missile sites buried hundreds, even thousands, of feet below ground. The Pyongyang metro, for instance, lies more than 300 feet underground—beyond the reach of the MOP. Some North Korean facilities are thought to be protected by over a thousand feet of solid rock, making them virtually untouchable by conventional means.
In response, the Air Force has awarded a contract to Applied Research Associates (ARA), a New Mexico-based research and engineering firm, to design and prototype a next-generation air-to-ground penetrator weapon system. The contract, announced in early September 2025, is set to run for two years and will see ARA producing and testing both sub-scale and full-scale prototype munitions. The goal? To evaluate new capabilities against hard and deeply buried targets that continue to challenge U.S. national security.
"ARA will also produce and test sub-scale and full-scale prototype munitions," the company stated, emphasizing the importance of developing weapons capable of tackling the toughest underground fortifications. Boeing, the aerospace giant responsible for the original MOP, has been tapped to design and develop the tail kit for the new bomb, further underscoring the collaborative effort behind this next-generation weapon.
Details about the new bomb, dubbed the Next Generation Penetrator (NGP), remain closely guarded. However, documents and requests from the Air Force reveal some key requirements. The NGP must not exceed 22,000 pounds—significantly lighter than the MOP—while delivering powerful blast and fragmentation effects. Accuracy is paramount, with a navigation system designed to operate even in GPS-denied environments, a nod to lessons learned from recent conflicts where signal jamming has caused U.S.-made GPS-guided bombs to go astray. The Air Force is also requesting advanced guidance systems and smart “void-counting” fuzes that can detect hollow spaces in rock and only detonate at the desired depth or floor, greatly increasing the weapon’s effectiveness and precision.
Unlike the old brute-force approach—where, as Popular Mechanics puts it, “bigger is better” and the MOP acts like a giant club—the new NGP is expected to be smarter and more versatile. It may be capable of gliding or even self-propulsion, allowing it to strike targets from tens of miles away. This would enable bombers to remain at a safer distance, reducing their exposure to enemy defenses. The B-2 bomber, currently the only U.S. aircraft able to carry the MOP (storing two internally to preserve its stealth), may soon be joined by the upcoming B-21 Raider, which is expected to carry one NGP.
But the technological arms race doesn’t stop with smarter, lighter bombs. The Pentagon’s Defense Threat Reduction Agency (DTRA) is expanding its toolkit to include a range of new weapons and tactics. As adversaries dig deeper and use ultra-high-performance reinforced concrete, the U.S. is exploring new alloys like Military Steel and experimenting with bomb nose shapes to improve “terradynamics”—essentially, how a bomb can fly with less resistance through rock. Experiments suggest these innovations could allow future bunker busters to punch through even the toughest targets.
DTRA is also developing specialized munitions such as ADTROL (Active Denial for Targets Right of the Line), designed to collapse tunnel entrances and fill passageways with rubble, rendering underground facilities unusable. There’s also a focus on electromagnetic pulse (EMP) weapons, which can disable electronics deep inside bunkers by sending destructive currents through antennas, power lines, plumbing, and ventilation ducts—essentially turning a facility’s own infrastructure against it. According to Popular Mechanics, DTRA already has a developed prototype EMP weapon ready for testing, and protecting an entire facility from EMP attacks remains a daunting challenge for adversaries.
The Pentagon’s creative thinking extends to robotics as well. Between 2018 and 2021, DARPA ran the SubT Challenge, a competition to develop robotic systems capable of exploring and mapping subterranean spaces. While the technology is still emerging, analysts believe that robotic snakes and other machines could one day infiltrate underground targets, providing new ways to neutralize threats hidden far below the surface.
Of course, not every underground facility is buried beyond the MOP’s reach. The Massive Ordnance Penetrator, with its 20.5-foot length, 31.5-inch diameter, and 6,000-pound warhead, remains the largest non-nuclear bomb in the U.S. arsenal and is still effective against targets up to around 200 feet deep. Developed about 15 years ago with Iran’s Fordow nuclear site in mind, the MOP’s legacy continues, but the focus is clearly shifting to more advanced and adaptable solutions.
As the U.S. military prepares for future confrontations with adversaries like Iran, North Korea, and China, the development of the Next Generation Penetrator and other emerging technologies signals a commitment to staying ahead in the race to defeat hard and deeply buried targets. The battlefield is moving underground, and with it, the tools of war are evolving—becoming smarter, more precise, and, perhaps most importantly, more unpredictable for those who would seek to hide their most critical assets beneath layers of rock and concrete.
With new contracts awarded, prototypes in development, and a growing arsenal of specialized weapons, the United States is making it clear: no bunker is too deep, no facility too fortified, for the next generation of American military might.
