Pentagon reveals video of how massive bunker buster bombs that wrecked Iranian nuclear facility work

Senior Defense Department officials described how the bombs used against the Iranian nuclear facility in Fordow worked during a Thursday press briefing at the Pentagon.

The United States struck facilities in Fordow, Natanz and Isfahan related to Iran’s efforts to develop nuclear weapons early Sunday morning local time, using as many as 14 GBU-57 Massive Ordnance Penetrators in the operation, which involved a 37-hour flight by seven B-2A Spirit bombers. Air Force Gen. Dan “Razin” Caine, the chairman of the Joint Chiefs of Staff, told reporters the story of the bombs used to hit Fordow began in 2009 prior to showing a video of a test of the weapon.

“They just kept grinding it out and along the way, they realized we did not have a weapon that could adequately strike and kill this target, so they began a journey to work with industry and other tacticians to develop the GBU-57. They tested it over and over again, tried different options, tried more after that,” Caine told reporters. “They accomplished hundreds of test shots and dropped many full-scale weapons against extremely realistic targets for a single purpose, kill this target at the time and place of our nation’s choosing. And then, on a day in June of 2025, more than 15 years after they started their life’s work, the phone rang and the president of the United States ordered the B-2 force that you supported to go strike and kill this target.”

“Yesterday, I had honor and privilege of spending time with these two Defense Threat Reduction Agency officers who have given so much,” Caine continued. “One of them said, ‘I can’t even get my head around this, my heart is so filled with the pride of being a part of this team, I’m so honored to be a part of this. To you both, thank you and thank you to your families.”

WATCH:

The GBU-57 is a GPS-guided bomb weighing 27,125 pounds carrying 5,342 pounds of high explosive that can be carried on the B-2, according to Designation-Systems.net. Caine displayed a video of how the GBU-57 worked.

“Let me talk about the graphic a little bit and the GBU-57, which all of you know is 30,000-pound weapon dropped only by the B-2. It is comprised of steel, explosive and a fuse programmed bespokely to achieve a particular effect inside the target. Each weapon had a unique desired impact angle, arrival, final heading and a fuse setting,” Caine said. “The fuse is effectively tells the bomb when to function. A longer delay in a fuse, the deeper the weapon will penetrate and drive into the target. So, on Fordow, in June of 2008, you can see these three holes depicted here as the main exhaust shaft with two additional ventilation shafts on either side. The United States decided to strike two ventilation shafts seen here on main graphic as primary point of entry into the mission space.”

“In the days preceding the attack against Fordow, the Iranians attempted to cover the shafts with concrete to try to prevent an attack. I won’t share specific dimensions of the concrete cap, but you should know that we know what the dimensions of those concrete caps were,” Caine continued. “The planners had to account for this, they accounted for everything. The cap was forcibly removed by the first weapon and the main shaft was uncovered. Weapons two, three, four, five were tasked to enter the main shaft, move down into the complex at greater than 1,000 feet per second and explode in the mission space. Weapon number six was designed on each side so six on each side, weapons number six designed as a flex weapon to allow us to cover if one of the preceding jets or one of the preceding weapons did not work. The video I’m about to show you is a culmination of over 15 years of development and testing, as I said, hundreds of test shots on various models. This is one weapon, so if you take a view of this as five additional, you will get a sense of what this looks like.”

Israel launched a military operation targeting the Iranian nuclear program on June 12, after efforts to secure a cessation of Iran’s nuclear program through diplomacy failed, striking nuclear facilities and targeting the theocratic regime’s top nuclear scientists and military commanders.

Gen. Dan “Razin” Caine demonstrates how GBU-57 MOPs work: “Unlike a normal surface bomb, you won’t see an impact crater because they’re designed to deeply bury and then function … All six weapons at each vent at Fordow went exactly where they were intended to go.” pic.twitter.com/iQs3oWcJ4X

— Rapid Response 47 (@RapidResponse47) June 26, 2025

“Unlike a normal surface bomb, you won’t see an impact crater, because they are designed to deeply bury and then function. I know there has been a lot of questions about that. All six weapons at each vent at Fordow went exactly where they were intended to go. A bomb has three effects that causes damage: Blast, fragmentation and overpressure,” Caine said. “In this case, the primary kill mechanism in the mission space was mix of overpressure and blast ripping through the open tunnels and destroying critical hardware. The majority of the damage we assess based on our extensive modeling was a blast layer combined with impulse extending from the shock. Imagine what this looks like six times over.”

“A point I want to make here, the joint force does not do BDA [bomb-damage assessment]. By design, we don’t grade our own homework, the intelligence community does,” Caine continued. “But here is what we know following the attack and the strikes on Fordow: First, that the weapons were built, tested and loaded properly. Two, the weapons were released on speed and on parameters. Three, the weapons all guided to intended targets and to their intended aimpoints. Four, weapons functioned as designed, meaning they exploded, we know this through other means, intelligence means we have that were visibly able to see them and we know that the trailing jets saw the first weapons function and pilots stated, quote, ‘This was the brightest explosion I’ve ever seen, it literally looked like daylight.’”

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