The United States quietly achieved a major technical and industrial milestone last year when it successfully reverse engineered a critical subcomponent of the 30,000-pound GBU-57/B Massive Ordnance Penetrator (MOP), the Pentagon’s most powerful conventional bunker-buster bomb. By leveraging technology originally developed for the Army Tactical Missile System, or ATACMS, the effort saved an estimated four years of design and development work and helped address growing obsolescence concerns inside one of America’s most strategically sensitive weapons programs.
The breakthrough, disclosed in a recent U.S. Air Force contracting justification document, highlights not only the continued operational importance of the GBU-57/B but also the mounting pressures created by long-standing “vendor lock” arrangements in the U.S. defense sector. As the Pentagon seeks to replenish MOP inventories following combat use during Operation Midnight Hammer, it is also confronting deeper structural questions about intellectual property (IP) ownership, sole-source contracting, and industrial flexibility.
According to a Justification & Approval (J&A) document issued by the Air Force Life Cycle Management Center (AFLCMC), the government successfully reverse engineered a key subcomponent of the MOP weapon system in August 2025. The effort enabled the use of existing technology from the Army Tactical Missile System (ATACMS), a short-range ballistic missile system long used by U.S. Army forces.
The document states that this reverse engineering initiative “saved four years of design work and enabled the utilization of existing Army ATACMS technology to eliminate obsolescence issues and meet operational demands.” However, it also warns that attempting to reverse engineer the entire MOP system would cause unacceptable delays in meeting mission requirements.
The ATACMS program is currently led by Lockheed Martin, which produces successive variants of the missile. While the Air Force did not specify which ATACMS-derived technology was adapted for MOP, the tail kit’s guidance and navigation components are the most likely candidates, given their reliance on GPS-assisted inertial navigation systems and hardened electronics capable of surviving extreme acceleration and stress.
Reverse engineering in defense programs is not unusual, particularly when suppliers exit the market or components become obsolete. But in the case of MOP, the effort underscores a more complicated challenge: dependence on a single prime contractor for key technical data and manufacturing processes.
The J&A document was produced as part of the Air Force’s effort to award a sole-source contract to Boeing, the current prime contractor for the MOP program. The contract covers additional production of tail kits and other components needed to replenish bombs expended during Operation Midnight Hammer.
During that operation, B-2 Spirit bombers dropped 14 GBU-57/B bombs on Iranian nuclear facilities, marking one of the most operationally significant uses of the weapon since its inception. Each B-2 can carry only two MOPs at a time, reflecting both the bomb’s immense size and the limited fleet of aircraft capable of deploying it.
The MOP’s tail kit, designated KMU-612/B, integrates the GPS-aided inertial navigation system and other critical control components. When combined with the BLU-127/B penetrating warhead and advanced fuzes, it forms the complete all-up-round (AUR) GBU-57/B weapon.
The Air Force estimates that designing and certifying a new tail kit from scratch would require roughly 60 months — five years — due to testing, validation, and operational certification requirements. That timeline is incompatible with current strategic demands, particularly amid renewed tensions with Iran and ongoing concerns about hardened underground facilities in countries such as North Korea and China.
At the heart of the issue is intellectual property ownership. According to the J&A document, Boeing — as the original equipment manufacturer — retains ownership of the technical data package (TDP), manufacturing methodologies, software, and other proprietary elements associated with the MOP tail kit.
The U.S. government does not own or control these data rights via license or other IP mechanisms. When queried in August 2025 about selling IP rights for the MOP system, Boeing reportedly declined.
Over the roughly 18 years of MOP development, the government has at times managed to break elements of the program away from sole-source dependence. For example, the warhead casing was separated under a weapon design agent effort, granting the government full IP control over that portion and allowing competitive contracting. However, the tail kit remains firmly within Boeing’s proprietary domain.
This arrangement has placed the Air Force in a position where replenishment and sustainment must proceed through a single vendor — even as obsolescence and supply chain pressures mount.
The precise size of the U.S. inventory of GBU-57/B bombs remains classified. As of 2015, at least 20 had been delivered, though subsequent production runs have occurred. In 2024, reports indicated that a facility in Oklahoma was being expanded to potentially triple or quadruple annual output.
MOP remains the only conventional munition capable of penetrating certain deeply buried and hardened targets, including underground nuclear enrichment facilities. From its inception, the weapon was designed with Iranian nuclear sites in mind, though its relevance extends to other adversaries that have invested heavily in subterranean infrastructure.
Iran, in particular, has reportedly taken new measures to further shield elements of its nuclear program from air and ground attack, increasing the premium on weapons capable of extreme penetration depth.
The GBU-57/B is also expected to be compatible with the forthcoming B-21 Raider, which will eventually replace or supplement the B-2 fleet. While the B-21 is smaller and may carry only one MOP per aircraft, its stealth and survivability characteristics will enhance the weapon’s operational flexibility.
The MOP program’s vendor lock challenges mirror those seen in the F-35 Lightning II program, also led by Lockheed Martin. The F-35 has long faced criticism over sustainment costs, spare parts bottlenecks, and the Pentagon’s limited control over key IP elements.
U.S. officials have repeatedly emphasized the operational risks created by heavy dependence on a single contractor. Foreign operators have likewise raised concerns about potential restrictions on software updates and sustainment pipelines in times of diplomatic strain.
These experiences have fueled a broader push within the Department of Defense to secure greater IP rights in future contracts and to enable third-party integration of components. Recent acquisition reform efforts aim to prevent prime contractors from retaining exclusive control over critical subsystems across an entire platform’s life cycle.
War Secretary Pete Hegseth stated last November that the Pentagon intends to enable qualified vendors to independently develop and integrate replacement modules at the component level, reducing bottlenecks and monopolistic practices.
The Pentagon is currently developing a successor to MOP known as the Next Generation Penetrator (NGP), with Boeing again involved in the effort. Lessons learned from the MOP’s IP and vendor lock constraints are expected to influence how NGP is structured contractually.
The reverse engineering of a critical MOP component using ATACMS technology demonstrates both the ingenuity and the limitations of current acquisition models. While the effort provided immediate operational relief and addressed obsolescence concerns, it did not fundamentally resolve the underlying IP dependency surrounding the tail kit.
For now, sole-source contracts remain necessary to ensure timely replenishment of high-value, low-density munitions like the GBU-57/B. But the broader policy momentum is clearly shifting toward greater competition, diversified supply chains, and government ownership of critical technical data.
As strategic competition intensifies and underground hardened facilities proliferate, the MOP will likely remain a central element of U.S. conventional deterrence. Whether future weapons can avoid the same vendor lock pitfalls may depend on how aggressively the Pentagon reforms its contracting frameworks in the years ahead.
