Massive Ordnance Penetrator

Extracted Attributes

• Mass

  30,000 pounds (14,000 kg)

• Name

  GBU-57 Massive Ordnance Penetrator (MOP)

• Type

  Precision-guided munition, Bunker buster bomb

• User

  United States Air Force (USAF)

• Length

  20.5 feet (6.2 meters)

• Diameter

  31.5 inches (0.80 meters)

• Variants

  Seven GBU-57 variants

• Bomb Body

  BLU-127

• Developer

  Boeing

• In Service

  2011-present

• Number Built

  At least 20 (as of 2015)

• Guidance System

  GPS/INS (Global Positioning System/Inertial Navigation System)

• Primary Purpose

  Destroy deeply buried weapons of mass destruction facilities, hardened bunkers, and tunnels

• Penetration Capability

  At least 200 feet (through concrete or bedrock)

• Warhead Explosive Charge

  Approximately 5,000-5,300 pounds

Timeline

• The GBU-57 Massive Ordnance Penetrator entered service. (Source: Wikipedia)

  2011

• At least 20 GBU-57 units had been contracted for production. (Source: Web Search)

  2015

• First combat use of the GBU-57 MOP during Operation Midnight Hammer, where seven Northrop B-2 Spirit bombers dropped 14 GBU-57 bombs on Iran's Fordow Uranium Enrichment Plant and Natanz Nuclear Facility. (Source: Prompt, Wikipedia, Related Document, Web Search)

  2025-06-22

GBU-57A/B MOP

The GBU-57 series MOP (Massive Ordnance Penetrator) is a 30,000-pound (14,000 kg) class, 20.5-foot-long (6.2 m) precision-guided munition "bunker buster" bomb—the initials "GBU" stand for "guided bomb unit"—developed by Boeing for the United States Air Force (USAF). Composed of a BLU-127 bomb body and an integrated GPS/INS guidance package, there are seven GBU-57 variants. Due to its size and weight, the GBU-57 MOP can only be carried by the Northrop B-2 Spirit strategic bomber and the B-21 Raider, although initial tests were conducted with the Boeing B-52 Stratofortress. The first combat use of the GBU-57 MOP came on June 22, 2025, when seven Northrop B-2 Spirit stealth bombers dropped 14 GBU-57 bombs on Iran's Fordow Uranium Enrichment Plant and Natanz Nuclear Facility. The bomb is much larger than earlier USAF bunker-busters such as the 5,000-pound (2,300 kg) GBU-28 and GBU-37.

Web Search Results

• Bunker Buster: How the Massive Ordnance Penetrator (MOP) Works

  The GBU-57 Massive Ordnance Penetrator (MOP) is a 30,000-pound class weapon designed to strike hardened, deeply buried targets. The MOP guides itself using a combination of GPS and an inertial navigation system, then impacts the surface at high speed while using a specialized steel alloy casing to “drill” through the ground, and finally detonates its roughly 5,000-pound warhead. The MOP can reportedly penetrate at least 200 feet, although newer models may be able to strike even deeper. If a [...] single MOP is unable to reach the target, additional MOPs could be dropped to penetrate deeper underground. The B-2 Spirit is the only aircraft in the U.S. inventory currently equipped to employ the MOP in combat and can carry two of the weapons, while the forthcoming B-21 Raider is expected to carry a single MOP. [...] ## Download Infographic ##### Bunker Buster: How the Massive Ordnance Penetrator (MOP) Works #### Issues: #### Issues:

• GBU-57A/B MOP - Wikipedia

  The GBU-57 series MOP (Massive Ordnance Penetrator) is a 30,000-pound (14,000 kg) class, 20.5-foot-long (6.2 m) precision-guided munition "bunker buster" bomb—the initials "GBU" stand for "guided bomb unit"—developed by Boeing for the United States Air Force (USAF). Composed of a BLU-127 bomb body and an integrated GPS/INS guidance package, there are seven GBU-57 variants. Due to its size and weight, the GBU-57 MOP can only be carried by the Northrop B-2 Spirit strategic bomber and the B-21 [...] | GBU-57A/B Massive Ordnance Penetrator | | | --- | --- | | GBU-57 MOP prototype | | | Type | Bunker buster | | Place of origin | United States | | Service history | | | In service | 2011–present | | Used by | United States Air Force | | Wars | Iran–Israel war | | Production history | | | Manufacturer | Boeing | | No. built | at least 20 | | Specifications | | | Mass | 27,125 lb (12,304 kg) | | Length | 20.5 ft (6.2 m) | | Diameter | 31.5 in (0.80 m) | | --- | | | Filling | AFX-757/PBXN-114 | [...] There has been debate over whether the GBU-57 Massive Ordnance Penetrator (MOP) can reliably destroy Iran's deeply buried nuclear sites. The Fordow facility and the new halls under construction at Natanz are thought to lie more than 80 m underground, whereas the original Natanz enrichment plant sits roughly 20 m below the surface.

• What to know about the MOP and the B-2, the bunker-buster bomb ...

  The bomb that Shaheen was referring to is the GBU-57 Massive Ordnance Penetrator, known as a MOP. It is designed to attack "deeply-buried facilities and hardened bunkers and tunnels," according to the Air Force. It's guided by military GPS and is meant to reach and destroy targets in well-protected facilities. The MOP measures about 20.5 feet in length and 31.5 inches in diameter, according to the Air Force. [...] Massive Ordnance Penetrator bomb -------------------------------- Image 2: Mideast Wars Bunker Buster Bombs In this photo released by the U.S. Air Force on May 2, 2023, airmen look at a GBU-57, or the Massive Ordnance Penetrator bomb, at Whiteman Air Base in Missouri. U.S. Air Force via AP, File [...] It's designed to penetrate up to 200 feet underground before exploding. The warhead is encased in a special high-performance steel alloy, which is meant to enable it to carry a large explosive payload while maintaining the penetrator case's integrity during impact, according to an Air Force fact sheet. Boeing developed the GBU-57, and as of 2015, the aerospace company had been contracted to produce 20 of them, according to the Air Force.

• Everything We Just Learned About The GBU-57 Massive Ordnance ...

  The Pentagon has shared extensive new information about the use of 30,000-pound GBU-57/B Massive Ordnance Penetrator (MOP) bunker buster bombs in recent strikes on Iran, a mission it says was 15 years in the making. Additional details have also been provided about how the specific need to hold the deeply buried Iranian enrichment facility at Fordow at risk was a primary design driver for the MOP program and its evolution. All of this comes amid still evolving and often competing assessments, at [...] ### Massive Ordnance Penetrator Bunker Buster Grows More Potent Massive Ordnance Penetrator Bunker Buster Grows More Potent By Joseph Trevithick 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. [...] The War Zone Logo The War Zone Logo # Everything We Just Learned About The GBU-57 Massive Ordnance Penetrator Strikes On Iran By Joseph Trevithick Updated Jun 26, 2025 2:07 PM EDT The Pentagon has shared extensive new information about the use of 30,000-pound GBU-57/B Massive Ordnance Penetrator (MOP) bunker buster bombs in recent strikes on Iran, a mission it says was 15 years in the making. DOD/USAF ## The TWZ Newsletter The TWZ Newsletter

• Why This Is the Only Bomb That Could Destroy Iran's Nuclear ...

  damage. The military required a more powerful weapon that would respect the “nuclear taboo,” a widely accepted international consensus that the use of nuclear weapons is morally abhorrent and dangerous because it creates radioactive fallout, invites escalation, and risks driving allies and neutral states into diplomatic revolt. GBU-57/B—also known as a Massive Ordnance Penetrator (MOP)—was a solution. Its Air Force fact sheet sums it up as “a weapon system designed to accomplish a difficult, [...] The first three letters in GBU-57/B stand for “guided bomb unit” (a precision bomb that can home in on its target), and it’s the 57th design in the series of such bombs. The second B refers to the bomb’s iteration (designations such as A/B, B/B, C/B, and so on are used for each adjustment made by military engineers). After the U.S.’s 2003 invasion of Iraq, engineers studied bunker strikes with smaller and older GBU models and found that they hadn’t penetrated deeply enough and had done limited [...] however, all that energy is concentrated into a tiny area. According to a 2012 Congressional Research Service briefing, the GBU-57/B has been reported to burrow through 200 feet of concrete or bedrock with a density of 5,000 pounds per square inch (comparable to the strength of bridge decks or parking-garage slabs). Then its 5,300-pound explosive charge detonates.

The GBU-57A/B Massive Ordnance Penetrator (MOP) is a precision-guided, 30,000-pound (14,000 kg) "bunker buster" bomb used by the United States Air Force. This is substantially larger than the deepest-penetrating bunker busters previously available, the 5,000-pound (2,300 kg) GBU-28 and GBU-37. It is designed to accomplish a difficult, complicated mission of reaching and destroying an adversary's weapons of mass destruction located in well-protected facilities.