Munitions

GBU-57A/B Massive Ordnance Penetrator

Also known as
  • GBU-57 MOP
  • GBU-57/B
  • Massive Ordnance Penetrator
  • MOP
  • 30,000-pound bunker buster

The GBU-57A/B Massive Ordnance Penetrator is a Boeing-built U.S. Air Force GPS-guided bunker-buster bomb for hardened and deeply buried facilities. Developed from a Defense Threat Reduction Agency technology demonstration and integrated for B-2 Spirit employment, it became operationally documented in June 2025 when U.S. B-2s used 14 weapons against Iranian nuclear target areas during Operation Midnight Hammer, an event tracked in both the catalog's U.S.-Iran and 2025 Israel-Iran conflict scopes.

GBU-57A/B Massive Ordnance Penetrator, Air-delivered deep-penetration guided bomb, Munitions
Image source: Off Loading of MOP Cropped

Role in Conflicts

2025 Israel-Iran Conflict
Long-Range Strike
Side
United States

During the June 2025 Israel-Iran conflict, U.S. B-2 Spirit bombers used 14 GBU-57 Massive Ordnance Penetrator bombs against the Fordow and Natanz nuclear target areas in Operation Midnight Hammer.

Profile / Specs

Profile

Origin
United States
Built by
Boeing
Type
Air-delivered deep-penetration guided bomb
Service note
Modern deep-penetration munition
Designer
Defense Threat Reduction Agency / Air Force Research Laboratory, with Boeing as industry partner
Designed
Technology demonstration work began in 2004; Air Force quick-reaction capability transition in 2010
Produced
Initial Air Force procurement and integration contracts from 2009-2010; later carriage, release, modification, and replenishment contracts through 2026
Developed into
GBU-76/B Next Generation Penetrator follow-on program

Specifications

Weight
30,000 lb class
Length
About 20 ft to 20.5 ft
Diameter
31.5 in
Explosive payload
More than 5,300 lb of explosive material in U.S. Air Force photo-caption data; Air & Space Forces Magazine reports a 5,740 lb warhead figure
Role
Deep-penetration precision weapon against hardened and deeply buried targets
Carrier aircraft
B-2 Spirit; DOT&E describes the B-2 as the only aircraft capable of employing MOP
Guidance
GPS-guided penetrating weapon with Large Penetrator Smart Fuze modification work documented by DOT&E
Program background
DTRA technology-demonstration testing began in 2004 and transitioned to the Air Force as a quick-reaction capability program in 2010
Warhead/body
BLU-127 warhead identified in Air Force procurement justification
Design And Employment Notes

The MOP is a specialized hard-target munition rather than a general-purpose blast bomb. Public U.S. Air Force and DOD material emphasizes defeat of hardened and deeply buried facilities, B-2 operational carriage, and DTRA modeling, testing, and validation work before transition to Air Force control.

Carriage

Public operational reporting ties combat release to B-2 Spirit bombers; earlier B-52 imagery documents test-release activity rather than operational carriage.

Target Set

The system is intended for protected WMD-related facilities, tunnels, bunkers, and other hardened or deeply buried targets.

Conflict Scope

Open sources directly document Operation Midnight Hammer use in June 2025. The same strike is represented in this catalog under the direct U.S.-Iran conflict scope and the wider 2025 Israel-Iran conflict scope, where the United States is listed as a conflict side.

Carrier And Test Aircraft

The public operational record ties GBU-57 combat employment to the B-2 Spirit; separate imagery documents B-52 test-release activity.

CarrierCarrier typeCarriage evidence
B-2 Spirit, Low-observable strategic heavy bomber, Aircraft & UAVsB-2 SpiritStealth bomber

DOT&E describes the B-2 as the only aircraft capable of employing MOP; Air National Guard reporting says B-2 Spirit bombers delivered 14 MOP bombs during Operation Midnight Hammer, and the Whiteman test article describes a B-2 three-ship loaded with two 30,000-pound GBU-57A/B weapons each.

Sources: DOT&E FY2025 Annual Report - Massive Ordnance Penetrator Modification, Missouri Guard Airmen Play Critical Role in Iran Nuclear Strike Mission, B-2 three-ship satisfies test objectives

B-52 Stratofortress, Long-range heavy bomber, Aircraft & UAVsB-52 StratofortressTest aircraft

A public-domain U.S. military image caption identifies a B-52 releasing a test version of the MOP over White Sands Missile Range in 2009; this documents test-release activity, not operational GBU-57 carriage.

Sources: B-52 releases the MOP during a weapons test

Timeline

GBU-57A/B Massive Ordnance Penetrator Key Events

  1. DTRA technology-demonstration testing begins

    The U.S. Air Force fact sheet says early MOP tests began in 2004 under a Defense Threat Reduction Agency technology-demonstration effort with the Air Force Research Laboratory.

    Sources: Massive Ordnance Penetrator

  2. Static tunnel lethality test completed

    Boeing-origin reporting archived by Deagel describes a Boeing-developed MOP static tunnel lethality test at DTRA's White Sands weapons tunnel complex.

    Sources: Massive Ordnance Penetrator Static Lethality Test

  3. Air Force quick-reaction capability transition

    The DTRA MOP technology-demonstration effort transitioned to the Air Force as a quick-reaction capability program in February 2010.

    Sources: Massive Ordnance Penetrator

  4. Large Penetrator Smart Fuze quick-reaction work begins

    DOT&E says the Air Force established the MOP Modification quick-reaction capability in August 2018 after a July 2018 urgent operational need for the Large Penetrator Smart Fuze.

    Sources: DOT&E FY2024 Annual Report - Massive Ordnance Penetrator Modification

  5. Smart-fuze and B-2 integration tests continue

    DOT&E reported FY2024 subscale lethality testing, full-scale LPSF testing, and B-2 integration-issue testing as part of the MOP Modification program.

    Sources: DOT&E FY2024 Annual Report - Massive Ordnance Penetrator Modification

  6. First operational employment in Operation Midnight Hammer

    U.S. officials said B-2s dropped 14 30,000-pound GBU-57 Massive Ordnance Penetrators against Iranian nuclear target areas during Operation Midnight Hammer, and DOT&E later said all 14 met release parameters, guided accurately, and functioned as intended.

    Sources: Secretary of Defense Pete Hegseth and Chairman of the Joint Chiefs of Staff General Dan Caine Hold a Press Conference, DOT&E FY2025 Annual Report - Massive Ordnance Penetrator Modification, The Weapons of Operation Midnight Hammer: MOPs, Tomahawks, and More

  7. DOT&E removes MOP Modification from oversight

    After the June 2025 real-world employment, DOT&E reported that it removed the MOP Modification program from oversight in July 2025 while still recommending continued LPSF test-and-evaluation funding.

    Sources: DOT&E FY2025 Annual Report - Massive Ordnance Penetrator Modification

  8. Replenishment contract reporting follows combat expenditure

    The Defense Department announced a sole-source Boeing replenishment contract for GBU-57 weapon systems, KMU-612 E/B tail kits, fuze-system cable guides, separation nuts, and MOP containers.

    Sources: Contracts for Feb. 24, 2026

  9. GBU-76/B follow-on designation reported

    Air & Space Forces Magazine reported that the Air Force designated the Next Generation Penetrator as GBU-76/B and was seeking sources for design, production, testing, and sustainment support for the MOP follow-on.

    Sources: Air Force Reveals Designation for Next-Gen Bunker Buster

Program Status And Follow-On

Public reporting after Operation Midnight Hammer shows the GBU-57 record moving in two directions at once: replenishment of the expended MOP inventory and planning for a lighter follow-on penetrator.

Post-strike assessment

DOT&E reported that all 14 GBU-57 weapons in the June 2025 strike met release parameters, guided accurately to their aimpoints, and functioned as intended.

Replenishment

The February 2026 Boeing contract covered GBU-57 weapon systems plus tail kits, fuze-system cable guides, separation nuts, and containers.

Successor path

The Air Force later identified the Next Generation Penetrator as GBU-76/B, a planned successor intended to continue the hard-target mission while potentially changing weight and carrier options.

Media

GBU-57A/B Massive Ordnance Penetrator Videos

GBU-57A/B Massive Ordnance Penetrator Images

GBU-57A/B Massive Ordnance Penetrator, Air-delivered deep-penetration guided bomb, Munitions - view 1
Source: B-52 releases the MOP during a weapons test
Related Weapon Systems
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Sources

Massive Ordnance PenetratorPublisher: U.S. Air Force | Note: Supports GBU-57 mission, program background, DTRA transition, Boeing contract context, and specifications. | Accessed: 2026-07-1330,000-pound bomb reaches milestonePublisher: U.S. Air Force | Note: Supports MOP dimensions, approximate weight, explosive-material figure, B-2 load-trainer context, and public-domain photo-caption data. | Accessed: 2026-07-13Massive Ordnance Penetrator Static Lethality TestPublisher: Deagel | Note: Archives Boeing release text on the March 2007 static tunnel lethality test at DTRA's White Sands weapons tunnel complex. | Accessed: 2026-07-13Missouri Guard Airmen Play Critical Role in Iran Nuclear Strike MissionPublisher: Air National Guard | Note: Supports 2020 United States-Iran Conflict and 2025 Israel-Iran Conflict direct use by U.S. B-2 Spirit bombers when they delivered 14 GBU-57/MOP bombs during Operation Midnight Hammer. | Accessed: 2026-07-13B-2 three-ship satisfies test objectivesPublisher: Whiteman Air Force Base | Note: Supports B-2 integration and 30,000-pound GBU-57A/B test-load context. | Accessed: 2026-07-13The Weapons of Operation Midnight Hammer: MOPs, Tomahawks, and MorePublisher: Air & Space Forces Magazine | Note: Directly supports 2020 United States-Iran Conflict and 2025 Israel-Iran Conflict use by reporting that U.S. B-2s used GBU-57 MOPs during Operation Midnight Hammer; also supports dimensions and warhead-weight context. | Accessed: 2026-07-13Secretary of Defense Pete Hegseth and Chairman of the Joint Chiefs of Staff General Dan Caine Hold a Press ConferencePublisher: U.S. Department of Defense | Note: Directly supports 2020 United States-Iran Conflict and 2025 Israel-Iran Conflict use by documenting U.S. B-2 release of 14 GBU-57 weapons against Fordow and Natanz during Operation Midnight Hammer. | Accessed: 2026-07-13Defense Agency Contributed Toward Operation Midnight Hammer SuccessPublisher: U.S. Department of Defense | Note: Supports DTRA development and validation background and directly supports 2020 United States-Iran Conflict and 2025 Israel-Iran Conflict use by U.S. B-2s carrying 14 GBU-57 bombs in Operation Midnight Hammer. | Accessed: 2026-07-13CRS 2025 Israel-Iran Conflict, U.S. Strikes, and CeasefirePublisher: Congressional Research Service via EveryCRSReport.com | Note: Directly supports 2025 Israel-Iran Conflict use by reporting that the United States used GBU-57 Massive Ordnance Penetrator weapons with B-2 Spirit bombers in June 2025 air strikes on Iranian nuclear sites. | Accessed: 2026-07-13Air Force drops 14 MOP bombs on Iranian nuclear sites during first operational use of the weaponPublisher: DefenseScoop | Note: Directly supports 2020 United States-Iran Conflict and 2025 Israel-Iran Conflict use by reporting that GBU-57 Massive Ordnance Penetrator bombs were used by U.S. Air Force B-2 bombers against Iranian nuclear sites during Operation Midnight Hammer. | Accessed: 2026-07-13GBU-57 Massive Ordinance Penetrator TestPublisher: DVIDS | Note: Supports Air Force and DTRA test-video context for the GBU-57 weapon system and public-domain DOD media provenance; title spelling follows the DVIDS record. | Accessed: 2026-07-13DOT&E FY2025 Annual Report - Massive Ordnance Penetrator ModificationPublisher: Director, Operational Test and Evaluation | Note: Supports GPS-guided weapon description, hard-and-deeply-buried target mission, B-2-only employment statement, Large Penetrator Smart Fuze modification context, and direct 2020 United States-Iran Conflict and 2025 Israel-Iran Conflict use by documenting the June 2025 B-2 strike employment of 14 GBU-57 weapons. | Accessed: 2026-07-13DOT&E FY2024 Annual Report - Massive Ordnance Penetrator ModificationPublisher: Director, Operational Test and Evaluation | Note: Supports Large Penetrator Smart Fuze quick-reaction capability timing, FY2024 smart-fuze and B-2 integration testing, GPS-guided hard-target mission context, and Boeing Defense, Space & Security major-contractor context. | Accessed: 2026-07-13FY 2011 Procurement Program - MOPPublisher: U.S. Air Force Financial Management & Comptroller | Note: Supports GBU-57 precision GPS-guided penetrator description, BLU-127 warhead, DTRA technology-demonstration origin, Air Force QRC production, and FY2009 Boeing/St. Charles procurement data. | Accessed: 2026-07-13Contracts for Feb. 24, 2026Publisher: U.S. Department of War | Note: Supports Boeing replenishment contract for GBU-57 MOP weapon systems, KMU-612 E/B tail kits, GBU-57 G/B fuze-system cable guides, separation nuts, containers, work location, and completion window. | Accessed: 2026-07-13Air Force Reveals Designation for Next-Gen Bunker BusterPublisher: Air & Space Forces Magazine | Note: Supports GBU-76/B Next Generation Penetrator follow-on context and public reporting that the GBU-57 MOP was first used operationally during Operation Midnight Hammer. | Accessed: 2026-07-13Off Loading of MOP CroppedPublisher: Wikimedia Commons | Note: Supports public-domain U.S. military image provenance for the GBU-57/MOP image. | Accessed: 2026-07-13B-52 releases the MOP during a weapons testPublisher: Wikimedia Commons | Note: Supports public-domain U.S. Air Force image provenance for the gallery test-release image and B-52 test-release relationship context. | Accessed: 2026-07-13