GBU-57A/B MOP

==Combat use==

==Combat use==

===US airstrikes on Iranian nuclear facilities===

===US airstrikes on Iranian nuclear facilities===

There has been significant debate over whether the GBU-57 Massive Ordnance Penetrator (MOP) can reliably destroy Iran’s deeply buried nuclear sites at Natanz and Fordow. 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.<ref name="NotSure">{{cite magazine |title=America's huge bunker-busting bomb is not sure to work in Iran |url=https://www.economist.com/graphic-detail/2025/06/18/americas-huge-bunker-busting-bomb-is-not-sure-to-work-in-iran |website=www.economist.com}}</ref>

There has been significant debate over whether the GBU-57 Massive Ordnance Penetrator (MOP) can reliably destroy Iran’s deeply buried nuclear sites at Natanz and Fordow. 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.<ref name="NotSure">{{cite magazine |title=America's huge bunker-busting bomb is not sure to work in Iran |url=https://www.economist.com/graphic-detail/2025/06/18/americas-huge-bunker-busting-bomb-is-not-sure-to-work-in-iran |website=www.economist.com}}</ref>

The MOP is reportedly able to penetrate through about 18 m of reinforced concrete with a compressive strength of 5,000 psi.<ref name="2025-BBC-Fordo">{{Cite web |last=BBC Verify and the Visual Journalism team |date=June 18, 2025 |title=Iran's secretive nuclear site that only a US bomb could hit |url=https://www.bbc.co.uk/news/resources/idt-868e3c3d-25ec-43cb-bcc0-8832464b91ca |archive-url=https://web.archive.org/web/20250620075543/https://www.bbc.co.uk/news/resources/idt-868e3c3d-25ec-43cb-bcc0-8832464b91ca |archive-date=2025-06-20 |access-date=June 22, 2025 |website=BBC News |publisher=BBC |quote="The MOP’s heavy casing and weight allows it to penetrate about 18m of concrete or 61m of earth before exploding, according to analysts at Janes"}}</ref><ref>{{cite web |title=GBU-57/B Massive Ordnance Penetrator (MOP) |url=https://www.globalsecurity.org/military/systems/munitions/mop.htm |website=www.globalsecurity.org}}</ref> Iranian domestic research has produced concrete exceeding 30,000 psi, a level that could sharply reduce the bomb’s effective penetration depth.<ref name="NotSure"/> Complicating matters further is the possibility of deflection or yaw caused by advanced bunker-shell construction techniques.<ref>{{cite web |title=Bunker Buster Bomb Myth / MIT Prof Ted Postol & Lt Col Daniel Davis |url=https://www.youtube.com/watch?v=TriASB-F5UY |website=www.youtube.com}}</ref>

The MOP is reportedly able to penetrate through about 18 m of reinforced concrete with a compressive strength of 5,000 psi.<ref name="2025-BBC-Fordo">{{Cite web |last=BBC Verify and the Visual Journalism team |date=June 18, 2025 |title=Iran's secretive nuclear site that only a US bomb could hit |url=https://www.bbc.co.uk/news/resources/idt-868e3c3d-25ec-43cb-bcc0-8832464b91ca |archive-url=https://web.archive.org/web/20250620075543/https://www.bbc.co.uk/news/resources/idt-868e3c3d-25ec-43cb-bcc0-8832464b91ca |archive-date=2025-06-20 |access-date=June 22, 2025 |website=BBC News |publisher=BBC |quote="The MOP’s heavy casing and weight allows it to penetrate about 18m of concrete or 61m of earth before exploding, according to analysts at Janes"}}</ref><ref>{{cite web |title=GBU-57/B Massive Ordnance Penetrator (MOP) |url=https://www.globalsecurity.org/military/systems/munitions/mop.htm |website=www.globalsecurity.org}}</ref> Iranian domestic research has produced concrete exceeding 30,000 psi, a level that could sharply reduce the bomb’s effective penetration depth.<ref name="NotSure"/> Complicating matters further is the possibility of deflection or yaw caused by advanced bunker-shell construction techniques.<ref>{{cite web |title=Bunker Buster Bomb Myth / MIT Prof Ted Postol & Lt Col Daniel Davis |url=https://www.youtube.com/watch?v=TriASB-F5UY |website=www.youtube.com}}</ref>

The first combat use of the GBU-57 MOP was during the [[United States strikes on Iranian nuclear sites]] on June 22, 2025,<ref name="NYT20250622">{{Cite web |last=Cooper |first=Helene |date=June 21, 2025 |title=U.S. Military Is Pulled Back Into Middle East Wars |url=https://www.nytimes.com/2025/06/21/us/politics/military-middle-east-wars.html |access-date=June 22, 2025 |website=[[The New York Times]] |quote=The attack was the first time the U.S. military had used the weapon in combat.}}</ref><ref>{{Cite news |last=Allison |first=George |date=June 22, 2025 |title=B-2 stealth bombers strike Iran's nuclear facilities |url=https://ukdefencejournal.org.uk/b-2-stealth-bombers-strike-irans-nuclear-facilities/ |access-date=June 22, 2025 |work=UK Defence Journal}}</ref> when seven [[Northrop B-2 Spirit]] [[Stealth Bombers|stealth bombers]] dropped a total of fourteen GBU-57 bombs, twelve on the [[Fordow Uranium Enrichment Plant]] and two on the [[Natanz Nuclear Facility]].<ref name="Mongilio 2025">{{Cite news |last1=Mongilio |first1=Heather |last2=Lagrone |first2=Sam |date=June 22, 2025 |title=Operation Midnight Hammer Drops 14 Bunker Busters in Record B-2 Strike Against Iranian Nuclear Sites |url=https://news.usni.org/2025/06/21/u-s-strikes-3-iranian-nuclear-sites-using-b-2s-sub-launched-tomahawks |access-date=June 22, 2025 |work=USNI News |publisher=U.S. Naval Institute |location=Annapolis, Maryland}}</ref><ref>{{Cite web |title=U.S. Bombs Iran Live Updates: Trump Says Iran's Nuclear Sites "Completely and Totally Obliterated" in Speech |url=https://www.wsj.com/livecoverage/iran-israel-conflict-latest-news |access-date=2025-06-22 |website=WSJ |language=en-US}}</ref>

The first combat use of the GBU-57 MOP was during the [[United States strikes on Iranian nuclear sites]] on June 22, 2025,<ref name="NYT20250622">{{Cite web |last=Cooper |first=Helene |date=June 21, 2025 |title=U.S. Military Is Pulled Back Into Middle East Wars |url=https://www.nytimes.com/2025/06/21/us/politics/military-middle-east-wars.html |access-date=June 22, 2025 |website=[[The New York Times]] |quote=The attack was the first time the U.S. military had used the weapon in combat.}}</ref><ref>{{Cite news |last=Allison |first=George |date=June 22, 2025 |title=B-2 stealth bombers strike Iran's nuclear facilities |url=https://ukdefencejournal.org.uk/b-2-stealth-bombers-strike-irans-nuclear-facilities/ |access-date=June 22, 2025 |work=UK Defence Journal}}</ref> when seven [[Northrop B-2 Spirit]] [[Stealth Bombers|stealth bombers]] dropped a total of fourteen GBU-57 bombs, twelve on the [[Fordow Uranium Enrichment Plant]] and two on the [[Natanz Nuclear Facility]].<ref name="Mongilio 2025">{{Cite news |last1=Mongilio |first1=Heather |last2=Lagrone |first2=Sam |date=June 22, 2025 |title=Operation Midnight Hammer Drops 14 Bunker Busters in Record B-2 Strike Against Iranian Nuclear Sites |url=https://news.usni.org/2025/06/21/u-s-strikes-3-iranian-nuclear-sites-using-b-2s-sub-launched-tomahawks |access-date=June 22, 2025 |work=USNI News |publisher=U.S. Naval Institute |location=Annapolis, Maryland}}</ref><ref>{{Cite web |title=U.S. Bombs Iran Live Updates: Trump Says Iran's Nuclear Sites "Completely and Totally Obliterated" in Speech |url=https://www.wsj.com/livecoverage/iran-israel-conflict-latest-news|access-date=July 6, 2025|website=The Wall Street Journal}}</ref>

[[Dan Caine|General Dan Caine]] stated during a news conference on June 26, 2025, that "... the US military had specially developed the MOP to deal with [[Fordow Uranium Enrichment Plant]] after learning about its construction nearly 15 years ago."<ref>{{Cite web |last=King|first=Ryan |date=June 25, 2025 |title=How the US bomber pilots reacted to historic strike on Iran nuclear sites |url=https://nypost.com/2025/06/26/us-news/how-the-us-b-2-bomber-pilots-reacted-to-historic-bombing-on-iran-nuclear-sites/ |access-date=2025-06-25 |website=NY Post |language=en}}</ref> Construction on the facility started in 2006, but the existence of the enrichment plant was only disclosed to the International Atomic Energy Agency (IAEA) by Iran in 2009 after the site became known to Western intelligence services;<ref>[http://www.iaea.org/Publications/Documents/Board/2009/gov2009-74.pdf GOV/2009/74] {{Webarchive|url=https://web.archive.org/web/20120515112958/http://www.iaea.org/Publications/Documents/Board/2009/gov2009-74.pdf |date=May 15, 2012 }} Implementation of the NPT Safeguards Agreement and relevant provisions of Security Council resolutions 1737 (2006), 1747 (2007), 1803 (2008) and 1835 (2008) in the Islamic Republic of Iran</ref><ref>{{Cite web |title=What is Iran's Fordow nuclear site and why is it so critical to the conflict? |url=https://www.euronews.com/2025/06/19/what-is-irans-fordow-nuclear-site-and-why-is-it-so-critical-to-the-conflict |access-date=June 19, 2025 |website=euronews.com}}</ref> however, the USAF asked defense contractors how they might develop a 30,000-pound, precision-guided bomb that could destroy targets deep underground or in hardened bunkers back in 2004.<ref>{{Cite news | url=https://edition.cnn.com/2004/US/07/20/big.bomb/ | title='Bunker busters' may grow to 30,000 pounds | first= Barbara | last=Starr | work=[[CNN]] | date=July 20, 2004}}</ref>

[[Dan Caine|General Dan Caine]] stated during a news conference on June 26, 2025, that "... the US military had specially developed the MOP to deal with Fordow Uranium Enrichment Plant after learning about its construction nearly 15 years ago."<ref>{{Cite web |last=King|first=Ryan |date=June 25, 2025 |title=How the US bomber pilots reacted to historic strike on Iran nuclear sites |url=https://nypost.com/2025/06/26/us-news/how-the-us-b-2-bomber-pilots-reacted-to-historic-bombing-on-iran-nuclear-sites/|access-date=July 6, 2025|website=New York Post}}</ref> Construction on the facility started in 2006, but its existence was only disclosed to the International Atomic Energy Agency (IAEA) by Iran in 2009 after the site became known to Western intelligence services;<ref>[http://www.iaea.org/Publications/Documents/Board/2009/gov2009-74.pdf GOV/2009/74] {{Webarchive|url=https://web.archive.org/web/20120515112958/http://www.iaea.org/Publications/Documents/Board/2009/gov2009-74.pdf |date=May 15, 2012 }} Implementation of the NPT Safeguards Agreement and relevant provisions of Security Council resolutions 1737 (2006), 1747 (2007), 1803 (2008) and 1835 (2008) in the Islamic Republic of Iran</ref><ref>{{Cite web |title=What is Iran's Fordow nuclear site and why is it so critical to the conflict? |url=https://www.euronews.com/2025/06/19/what-is-irans-fordow-nuclear-site-and-why-is-it-so-critical-to-the-conflict |access-date=June 19, 2025 |website=euronews.com}}</ref> however, the USAF asked defense contractors how they might develop a 30,000-pound, precision-guided bomb that could destroy targets deep underground or in hardened bunkers back in 2004.<ref>{{Cite news | url=https://edition.cnn.com/2004/US/07/20/big.bomb/ | title='Bunker busters' may grow to 30,000 pounds | first= Barbara | last=Starr | work=CNN| date=July 20, 2004}}</ref>

According to [[Dan Caine|General Dan Caine]], Chairman of the [[Joint Chiefs of Staff|U.S Joint Chiefs of Staff]], both sites sustained severe damage.<ref>{{Cite web |title=Bombing Inflicted Severe Damage, Pentagon Says |url=https://www.wsj.com/livecoverage/iran-israel-conflict-latest-news/card/bombing-inflicted-severe-damage-pentagon-says-xe3Zg4JYmAfTXLwad7tJ |access-date=2025-06-22 |website=WSJ |language=en-US}}</ref> Darya Dolzikova, Senior Research Fellow at [[RUSI]], argues that the exact damage to the facilities is unclear.<ref>{{cite web |title=RUSI Experts React to US Strikes on Iran's Nuclear Facilities |url=https://www.rusi.org/explore-our-research/publications/commentary/rusi-experts-react-us-strikes-irans-nuclear-facilities |website=www.rusi.org}}</ref> Rafael Grossi, director general in [[IAEA]] said “no one, including the IAEA, is in a position to have fully assessed the underground damage at Fordow”, it is expected to be “very significant”.<ref>{{cite web |title=UN nuclear chief estimates damage to Iran's facilities 'very significant' |url=https://www.aljazeera.com/news/2025/6/23/un-nuclear-chief-estimates-damage-to-irans-facilities-very-significant |website=www.aljazeera.com}}</ref>

According to General Dan Caine, Chairman of the [[Joint Chiefs of Staff|U.S Joint Chiefs of Staff]], both sites sustained severe damage.<ref>{{Cite web |title=Bombing Inflicted Severe Damage, Pentagon Says |url=https://www.wsj.com/livecoverage/iran-israel-conflict-latest-news/card/bombing-inflicted-severe-damage-pentagon-says-xe3Zg4JYmAfTXLwad7tJ|access-date=July 6, 2025|website=The Wall Street Journal}}</ref> Darya Dolzikova, Senior Research Fellow at [[RUSI]], argues that the exact damage to the facilities is unclear.<ref>{{cite web |title=RUSI Experts React to US Strikes on Iran's Nuclear Facilities |url=https://www.rusi.org/explore-our-research/publications/commentary/rusi-experts-react-us-strikes-irans-nuclear-facilities |website=www.rusi.org}}</ref> Rafael Grossi, director general in [[IAEA]] said “no one, including the IAEA, is in a position to have fully assessed the underground damage at Fordow”, it is expected to be “very significant”.<ref>{{cite web |title=UN nuclear chief estimates damage to Iran's facilities 'very significant' |url=https://www.aljazeera.com/news/2025/6/23/un-nuclear-chief-estimates-damage-to-irans-facilities-very-significant |website=www.aljazeera.com}}</ref>

CNN reported that the strikes "did not destroy the core components" of the facilities. This preliminary report was later refuted.<ref>{{Cite web |last1=Bertrand |first1=Natasha |last2=Lillis |first2=Katie Bo |last3=Cohen |first3=Zachary |date=June 24, 2025 |title=Exclusive: Early US intel assessment suggests strikes on Iran did not destroy nuclear sites, sources say {{!}} CNN Politics |url=https://www.cnn.com/2025/06/24/politics/intel-assessment-us-strikes-iran-nuclear-sites |access-date=2025-06-24 |website=CNN |language=en}}</ref>

CNN reported that the strikes "did not destroy the core components" of the facilities. This preliminary report was later refuted.<ref>{{Cite web |last1=Bertrand |first1=Natasha |last2=Lillis |first2=Katie Bo |last3=Cohen |first3=Zachary |date=June 24, 2025 |title=Exclusive: Early US intel assessment suggests strikes on Iran did not destroy nuclear sites, sources say {{!}} CNN Politics |url=https://www.cnn.com/2025/06/24/politics/intel-assessment-us-strikes-iran-nuclear-sites|access-date=July 6, 2025|website=CNN}}</ref>

==Specifications and capabilities==

==Specifications and capabilities==