--- title: "U.S. Used Its New 5,000-Pound Bunker Busters To Hit Iranian Anti-Ship Missile Sites: Reports" description: "The GBU-72/B sits between the common 2,000lb bunker buster and the far more powerful 30,000lb GBU-57/B Massive Ordnance Penetrator." date: "2026-03-18" modified: "2026-03-18" authors: - name: "Thomas Newdick" job_title: "Staff Writer" link: "https://www.twz.com/authors/thomas-newdick.md" - name: "Joseph Trevithick" job_title: "Deputy Editor" link: "https://www.twz.com/authors/joseph-trevithick.md" url: "https://www.twz.com/air/u-s-used-its-new-5000-pound-bunker-busters-to-hit-iranian-anti-ship-missile-sites-reports" categories: - "Air" - "Air Force Munitions" - "Air Forces" - "Air-To-Ground" - "Around The Globe" - "Bunker Busters" - "Iran" - "Joint Direct Attack Munition (JDAM)" - "Middle East" - "News & Features" - "U.S. Air Force" --- # U.S. Used Its New 5,000-Pound Bunker Busters To Hit Iranian Anti-Ship Missile Sites: Reports ![The U.S. Air Force has confirmed that it has, for the first time, used its new 5,000-pound-class GBU-72/B bunker-buster bomb in combat.]() *USAF* The U.S. Air Force is now reportedly dropping its newest bunker-buster bomb, the [5,000-pound class GBU-72/B](), on targets in Iran. The bombs are said to have been used in strikes on hardened Iranian anti-ship cruise missile sites along the highly strategic Strait of Hormuz overnight. There are also reports that this is the first time GBU-72/Bs have been used in combat, but it is not clear if this is the case. "Hours ago, U.S. forces successfully employed multiple 5,000-pound deep penetrator munitions on hardened Iranian missile sites along Iran’s coastline near the Strait of Hormuz," U.S. Central Command (CENTCOM) wrote in a post on X, which did not name the munitions in question, last night. "The Iranian anti-ship cruise missiles in these sites posed a risk to international shipping in the strait." https://twitter.com/CENTCOM/status/2034040698954031326 "US official confirms this was the GBU-72 Advanced 5K Penetrator," *CNN*'s Haley Britzky [subsequently wrote on X](). *Fox News* has also now reported the use of GBU-72/Bs in last night's strikes. https://twitter.com/lucasfoxnews/status/2034269869974122512?s=46 Whether or not the GBU-72/B has been employed in combat previously is unclear. In 2024, [*CBS News* reported]() that the Air Force had employed the bombs in strikes on an underground facility belonging to Iranian-backed Houthi militants in Yemen, citing unnamed officials. *Fox News* also reported again just today that the A5K's first use had come during previous strikes on the Houthis. There have also been reports in the past that Israel has [at least sought to acquire]() GBU-72/B, but whether any have been delivered to that country is unknown. It is also still not known what munitions were used in strikes [that left three very large and precise holes]() on the top of a site long linked to Iran’s nuclear program last week. The Israel Defense Forces (IDF) has said they struck that facility, but that does not automatically mean that U.S. forces did not do so, as well. When reached by *TWZ*, CENTCOM declined to comment on the specific munitions used in last night's strikes along the Strait of Hormuz. The GBU-72/B was developed to replace the older GBU-28/B, which first entered service in 1991. The GBU-28/B is another 5,000-pound class bunker buster, and it is unclear to what degree it remains in U.S. inventory. ![]() *An F-15E Strike Eagle drops a GBU-28/B bunker-buster bomb. *USAF** What aircraft are currently cleared to employ the GBU-72/B operationally is also not clear. In 2021, the Air Force announced the successful [release of an A5K from an F-15E]() Strike Eagle in testing. In 2024, [pictures emerged of a B-1 bomber carrying one]() of the bombs on [an external pylon]() under the forward fuselage in another apparent test. The Air Force [has also raised the possibility]() of integrating the GBU-72/B onto the B-2 bomber in the past. [F-15Es](), [B-1s](), and [B-2s]() are among the aircraft the U.S. military has been using to carry out strikes on targets in Iran. ![]() *An F-15E drops a GBU-72/B in a test. *USAF** In terms of the bomb itself, the A5K combines a BLU-138/B penetrating warhead with a tail kit containing a GPS-assisted inertial navigation system (INS) guidance system. The tail kit is a variant of the one used on 2,000-pound class Joint Direct Attack Munition (JDAM) precision guided bombs. Markings seen on live BLU-138/Bs in imagery the Air Force has previously released show that each warhead weighs around 4,422 pounds, with approximately 1,066.8 pounds of that being a combination of PBXN-109 and AFX-757 explosives. As an aside, those [are the same two types of explosives used in]() the much larger 30,000-pound class BLU-127/B warhead for [the GBU-57/B Massive Ordnance Penetrator]() (MOP) bunker buster bomb. https://twitter.com/GuyPlopsky/status/1836329321302233427 "With enhanced survivability, increased lethality, smart fuzing and utilization of fielded JDAM Navigation tailkits, the GBU-72 significantly improved performance reducing the number of weapons required to achieve a kill at lower AUR \[all-up-round\] cost," according to [Air Force budget documents](). "A5K will replace the GBU-28." While the precise capabilities of the Air Force’s various bunker-busting munitions are a closely guarded secret, the original GBU-28/B bomb [reportedly had the ability]() to penetrate through more than 150 feet of earth and at least 15 feet of reinforced concrete. In some cases, multiple bunker busters can also be dropped on the same aim point in succession to help burrow deeper down to the desired depth. ![]() *An old but still interesting graphic compares the capabilities of the BLU-109/B bunker-buster warheads found on certain variants of the GBU-31/B, as well as the GBU-28/B and the much larger GBU-57/B Massive Ordnance Penetrator. *DOD via GlobalSecurity.org** In addition, the GBU-72/B, like the GBU-28/B before it, offers a conventional bunker-buster capability that sits between bombs that use 2,000-pound class BLU-109/B warheads and the MOP. GBU-31/B JDAMs with [BLU-109 warheads]() are [already known]() to [be in very active]() use [in strikes on targets in Iran](). https://twitter.com/Chris1603/status/2034195591215927485?s=20 ![]() *A stock picture of GBU-31/Bs with bunker-buster warheads. *USAF** With all this in mind, the GBU-72/B does offer the U.S. military a way to get after deeply buried or otherwise hardened targets in Iran (and anywhere else) that are beyond the reach of the BLU-109/B without having to use GBU-57/Bs. The MOP inventory is understood to be relatively small and largely reserved for [use against very high-priority targets](). Using GBU-72/Bs could also help ensure the destruction of a target, and do so with a smaller number of total munitions, compared to a strike employing 2,000-pound-class bunker busters. ![]() *A picture of the arena test of the warhead for the 5,000-pound-class GBU-72 bunker-buster bomb. *USAF** Regardless of the munitions used, U.S. strikes targeting Iranian anti-ship cruise missile sites on the edge of the Strait of Hormuz speak to efforts now to reopen that critical waterway to regular maritime traffic. So far, we have not seen any clear evidence of Iran using its arsenal of thousands of anti-ship cruise missiles, which could turn the Strait into a super weapons engagement zone. Many of these missiles can also be launched from the backs of trucks that are hard to distinguish from civilian types. [Iranian aerial drone, missile](), and [uncrewed boat attacks](), as well as [the threat of naval mines](), have already brought movement through the Strait to a virtual standstill. A small number of commercial vessels have continued making the transit, but very likely only with the approval of the regime in Tehran. This is already having [massive negative impacts on global energy markets](), as well as [the overall economies of Gulf Arab States](). https://twitter.com/MartinKelly/status/2034162993009991852 https://twitter.com/shashj/status/2034177912891482475 The U.S. military [has been exploring options]() for escorting convoys of commercial ships through the Strait, but this would still come with significant risks, as [*TWZ* has explored in the past](). U.S. President Donald Trump had initially appealed to allies and partners for help, but said yesterday [that no assistance was necessary]() after [receiving public rebukes]() from several countries. “I wonder what would happen if we ‘finished off’ what’s left of the Iranian Terror State, and let the Countries that use it, we don’t, be responsible for the so called ‘Straight?’ \[sic\],” Trump wrote today in a post on his Truth Social site. “That would get some of our non-responsive ‘Allies’ in gear, and fast!!!” https://twitter.com/atrupar/status/2034238956213080327 A further uptick in strikes on Iranian targets along the Strait of Hormuz, including deeply buried and hardened sites that could necessitate the use of GBU-72/Bs, may now be on the horizon. *Contact the author: thomas@thewarzone.com* ## Author Thomas Newdick is a staff writer at *TWZ*, where he covers military aviation, defense technology, weapons systems, and international security. Based in Berlin, Germany, he reports on conflicts, military modernization efforts, and emerging aerospace technologies around the world, with a particular interest in airpower and its role in contemporary warfare. His reporting is informed by deep expertise in modern and historical airpower, particularly in Europe, with a focus on military aviation, air campaigns, and aerospace developments across the continent and beyond. Over a journalism career spanning more than 25 years, Thomas has become known for making complex defense and aerospace topics accessible to a broad audience. His reporting combines technical expertise, historical context, and a focus on the real-world operational and strategic implications of military developments. ### Author social links [Twitter]()