Last year, the US government was able to reverse engineer a critical subcomponent for the 30,000-pound GBU-57/B massive ordnance penetrator (MOP) bunker buster bomb. Leveraging technology from the Army Tactical Missile System (ATACMS) short-range ballistic missile saved years of work that would otherwise have been required to “eliminate obsolescence issues and meet operational demands.” The reverse-engineering effort also highlights the impact of being locked into a single vendor, and underscores why the Pentagon is now pushing to change, if not end, the practice.
Details of the reverse-engineered component and other aspects of the MOP program were included in a recent US Air Force contract announcement regarding efforts to replenish stocks of those bombs after Operation Midnight Hammer. During that operation, B-2 Spirit stealth bombers dropped 14 GBU-57/Bs on Iranian nuclear facilities. The Air Force Life Cycle Management Center (AFLCMC) had to present a detailed justification for awarding a sole source contract to Boeing for the production of new MOPs and sustainment of the existing inventory. Boeing is the current prime contractor for the bomb. A redacted copy of that document is available online.
A B-2 Spirit stealth bomber drops a GBU-57/B Massive Ordnance Penetrator (MOP) during a test. USAF
“The government needs a follow-on for more production [redacted] MOP tail kits to replace spent units and reach the United States Air Force with estimated deliveries beginning on 10 January 2028 [redacted],” the so-called Justification and Acceptance (J&A) document states. “The government requires replenishment production of GBU-57 MOP weapon system components.”
It is unclear what the total size of the GBU-57/B inventory was before or after Operation Midnight Hammer. As of 2015, prime contractor Boeing had delivered at least 20 of the bombs, according to the Air Force. However, more orders have been reported over the years. In 2024, a story from Bloomberg A facility was expanded in Oklahoma to help triple or quadruple the annual production of these bombs.
The MOP’s tail kit, also designated KMU-612/B, contains the bomb’s GPS-assisted Inertial Navigation System (INS) guidance package and other systems. It is combined with the BLU-127/B penetrating “warhead” and other components, including advanced fuzes designed to help produce maximum destructive effect on the target after falling deep into the ground, to create the complete GBU-57/B bomb, or all-up-round (AUR).
“In August 2025, the government successfully reverse-engineered a critical subcomponent of the MOP weapon system, saving 4 years of design work and enabling the use of existing Army ATACMS technology to eliminate obsolescence issues and meet operational demands,” according to the J&A document. “However, the timing of reverse engineering all MOP components would result in unacceptable delays in meeting mission requirements.”
MOP J&A does not elaborate on the ATACMS technology in question or what company or companies may now be in line to produce the resulting subcomponents for the bombs. Lockheed Martin is the current prime contractor for the ATACMS, a family of short-range ballistic missiles that you can read more about here . It should also be noted that reverse-engineering parts of major US military weapons systems is not entirely uncommon, especially if the original source of the components in question has gone out of business or otherwise does not exist.
An ATACMS short-range ballistic missile. US Army
The J&A document says it will take an estimated 60 months, or five years, to create a completely new MOP tail kit design and then go through the necessary processes to certify it for operational use. It also explains why the KMU-612/B tail kit, in particular, is the focus of Boeing’s need to award a new single-source contract.
“Regarding IP [intellectual property] Right, The [Redacted] The company is an original equipment manufacturer (OEM) of the MOP weapon system and retains ownership of the intellectual property data related to the ammunition tail kit,” it explains. “Specifically, [redacted] The technical data package and manufacturing process methods of the Telkit unit are fully proprietary. [Redacted] MOP has uniquely specialized over ~18 years adapting this particular weapon to meet evolving mission requirements as it transitions from proof-of-concept to full operational capability. This expertise relates to, but is not limited to, knowledge of guidance algorithms, navigation systems, hardware components, specialized test equipment, and software critical to producing and maintaining the MOP weapon system.
“Other components and sub-components, as mentioned above, are proprietary [redacted] Since the establishment of this weapon system. USG [U.S. government] does not own or control by license or other IP rights, any computer software, methods, or technical drawings,” the document adds.[Redacted] The possibility of selling the IP rights to the USG for the MOP weapon system was asked in August 2025 and the USG declined.
That said, “During the ~18 years of MOP development in the AURs received today, the USG has, at certain times, been able to separate from the environment the sole source for this weapon with Boeing,” J&A notes. “The USG was able to break warhead cases for the MOP under the Weapons Design Agent effort, which gave the USG full IP control over the warhead TDP. The USG contracts competitively based on IP ownership of this TDP.”
A GBU-57/B was seen before impact during testing. DOD
The possibility of new U.S. strikes against targets in Iran, including deeply buried nuclear sites and other facilities, highlights the continued importance of depth and readiness of the GBU-57/B inventory. There is clear evidence that Iranian officials have taken new steps to protect key elements of the country’s nuclear program from future air or ground attacks. The MOP has been and continues to be the only conventional weapon capable of engaging many of these targets, and was specifically designed with top mind sites in Iran. A conflict with Iran is not the only scenario where bombs would be relevant. North Korea and China have also invested heavily in underground and other hard facilities.
Giant bunker busters are otherwise the definition of high-value, low-density weapons. Currently, they can only be deployed by B-2 bombers. Each B-2 can only carry two bombs at a time. The MOP is expected to be an important part of the arsenal of the future B-21 Raider, which is smaller than the B-2 and is expected to be able to carry one of these bunker busters.
The details in the MOP J&A document also underscore the broader issues surrounding IP rights and ‘vendor lock’ in the US defense contracting space that have increasingly come to the fore in recent years. Competition naturally creates opportunities to reduce costs and diversify the supply chain. A broad supplier base also offers advantages when it comes to scaling production of key sub-components and complete systems.
The most widely known example of the negative effects of vendor lock-in is the continued limitation of Lockheed Martin’s control over the F-35 Joint Strike Fighter program. Especially when it comes to timely sourcing of spare parts, and the operational risks this creates, US authorities have created maintenance and sustainment challenges. TWZ First explored the specific issues surrounding the F-35 in an in-depth feature.
Foreign F-35 operators, particularly in Europe, are now facing regular questions about what could happen to the jets if the US cuts off access to various sustainable pipelines in light of new diplomatic tensions with Washington. This past weekend, Dutch State Secretary for Defense Gijs Tuinman caused a stir when he claimed it would be possible to “jailbreak the F-35 like an iPhone if necessary,” which you can read more about here .
BIG: Dutch Defense Minister Gijs Tuinman indicated that software independence is possible for the F-35 jets.
He literally said you can “jailbreak” the F-35.
Asked whether Europe could amend it without US approval:
“That’s not the point…we’ll see if the Americans show that… pic.twitter.com/f11cGvtYsO
– Clash Report (@clashreport) February 15, 2026
In recent years, successive US administrations have secured more IP rights and ensured opportunities for competition key elements in negotiating new defense contractors. As an example, the Air Force previously made it clear that the acquisition of the F-47 sixth-generation stealth fighter was a top priority to avoid vendor lock-in on the F-35 program. President Donald Trump’s administration is now pursuing a host of new contract reforms to break private companies’ locks on programs like the Joint Strike Fighter.
“We will enable third-party integration without prime contractor constraints. Success will be measured by the ability of qualified vendors to independently develop, test and integrate replaceable — excuse me, replaceable modules at the component level throughout the system life cycle,” Secretary of War Pete Hegseth said in a speech last November. “There is no more complacency and no monopoly.”
At the time, Hegseth also acknowledged the Byzantine processes and other contract obstacles the U.S. military had created for itself over the years.
How the “single-source environment” surrounding the GBU-57/B continues to evolve remains to be seen. A successor to that bomb, the Next Generation Penetrator (NGP), is also now in development, and Boeing is also involved in that effort. The Pentagon’s experiences with the MOP, along with the new contract reform push, are likely to inform how replacement weapons are acquired.
Meanwhile, US officials continue to try to free elements of the MOP program from vendor lock-in, including now repurposing technology originally designed for the ATACMS short-range ballistic missile.
Contact the author: joe@twz.com
