U.S. Air Force B-2 stealth bombers have not dropped any GBU-57/B Massive Ordnance Penetrator (MOP) bunker buster bombs on Yemen’s Houthis since the Trump administration launched a renewed aerial campaign against them, two U.S. officials have told TWZ. Reports in the past day or so had said that MOPs, America’s largest conventional bomb, had been employed against the Houthis sometime earlier this month. Even if the 30,000-pound GBU-57/Bs had been dropped on the Yemeni militants, they are relatively prized and specialized weapons, the use of which would likely be extremely selective and very limited in scope.
TWZ raised the question of whether B-2s carrying 30,000-pound bunker busters might strike targets in Yemen, in large part to send signals to Iran, after some of the bombers were sent to strike the Houthis last year. The topic came back up again after six B-2s were deployed to the island of Diego Garcia in the Indian Ocean as part of a larger build-up of U.S. military forces in and around the Middle East last month.
Six B-2 bombers seen parked on the apron at the airfield on Diego Garcia earlier this year. PHOTO © 2025 PLANET LABS INC. ALL RIGHTS RESERVED. REPRINTED BY PERMISSION
Recent reporting from The Aviationist and multiple outlets saying that MOPs have been used against the Houthis traces to a Fox News television segment yesterday, which prompted TWZ to seek direct confirmation. A U.S. defense official subsequently told us that no MOPs have been employed on targets in Yemen in the past two months.
“Based on current knowledge of what munitions have been used and reports that have made it up the chain of command, my understanding is that the GBU-57 hasn’t been used during this ongoing operation,” a second U.S. official also told TWZ.
B-2s forward-deployed in Diego Garcia have flown missions targeting the Houthis using other as yet unspecified munitions. The exact mix of munitions B-2s dropped on Yemen during the strikes last year remains unknown. It is also worth noting here that, at the time of writing, the Pentagon has only held one press briefing on the current Yemen campaign since March 17.
A B-2 bomber drops a MOP during a test. USAF
TWZ has also recently examined satellite images of multiple tunnel complexes in Yemen suspected to be utilized by the Houthis and has seen no signs of major damage. At the same time, a lack of readily visible damage can be indicative of the use of bunker buster bombs, and commercially available satellite imagery has major limitations in spotting fine details that could result from such a strike.
None of this precludes the potential for B-2s to drop GBU-57/Bs on Houthi targets in Yemen in the future. As TWZ has highlighted in our past reporting about the recent deployment of the stealth bombers to Diego Garcia, as well as the B-2 strikes on Yemen last year, the MOP is inextricably linked to the signaling power of sending these aircraft to any region.
The B-2 is currently the only aircraft certified to operationally employ GBU-57/Bs, the design of which has been and continues to be upgraded, as you can read more about here. A single B-2 can carry just two of the huge bunker-buster bombers. The pairing of the stealth bombers and the MOP gives the United States a unique option for penetrating into heavily defended areas to launch conventional strikes on deeply buried and fortified targets, including ones in Iran.
A MOP seen right before hitting the ground during a test. DOD
However, while there have been reports of the steady acquisition of additional GBU-57/Bs, as well as work to expand prime contractor Boeing’s overall capacity to build the bombs, the total stockpile is still understood to be relatively small.
As such, any use of GBU-57/Bs against targets in Yemen would have to be gauged against the need to ensure sufficient stocks of the bombs would still be available for use in the event of other major contingencies. A limited use of MOPs against particularly deeply buried targets would still offer strategic signalling benefits, especially aimed toward Iran, as well as the opportunity to gather data about how well the weapons work in a real-world context. Questions have been raised in the past about whether certain underground facilities in Iran tied to that country’s nuclear program might be beyond the reach of MOP, or at least safe from complete destruction from their employment.
An inert MOP used for training. Missouri Air National Guard
Negotiations between the United States and Iran over the latter country’s nuclear ambitions are now underway, the progress of which will have impacts on any additional messaging using U.S. military capabilities, including possibly dropping MOPs on targets in Yemen. But should the choice be made to attack Iran, those prized, massive weapons will be needed for far more pressing targets than going after stockpiles of Houthi missiles and drones.
Contact the author: joe@twz.com