A U.S. Air Power B-2 Spirit is ready for operations forward of “Operation Midnight Hammer” at Whiteman Air Power Base in Missouri, June 2025.
509th Bomb Wing/USAF
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509th Bomb Wing/USAF
The infographics had been in all places within the run-up to Sunday’s early-morning strike on Iran’s nuclear services by American stealth bombers.
They depicted America’s bunker-busting bomb, generally known as the Huge Ordnance Penetrator, or GBU-57. It was being dropped from excessive above the Earth by a B-2 Spirit bomber. Then, the graphics confirmed it plowing a slim channel deep beneath the bottom — round 60 meters, or 200 ft — and erupting in an illustrated explosion.
Solely America had this 30,000-pound weapon. Solely America might hit Iran’s most deeply buried uranium enrichment web site at a spot known as Fordo. It was buried beneath almost 90 meters (round 300 ft) of rock, far deeper than Israeli bombs might penetrate.
There was just one downside — I wasn’t completely positive it could work.
ANALYSIS: There’s a LOT of stuff within the media proper now concerning the Huge Ordinance Penetrator–The American bunker buster that may get used on Iran’s deeply buried web site at Fordow.
Can it hit Fordow? I am unsure.
Here is why (WITH MATH). 🧵 pic.twitter.com/cKuyDUc82p
— Geoff Brumfiel (@gbrumfiel) June 17, 2025
Now it seems it could not have. In response to a still-classified evaluation by the Protection Intelligence Company, the bombs didn’t “obliterate” Iran’s Fordo enrichment web site as President Trump initially claimed. As an alternative, the strike did solely restricted harm to the superior centrifuges stored there. At most, this system was set again “a couple of months,” in keeping with a U.S. official who confirmed the evaluation’s existence to NPR however remained nameless as a result of they weren’t licensed to talk to the press.
Yesterday, the White Home disputed that declare.
“The leaking of this alleged evaluation is a transparent try and demean President Trump,” White Home press secretary Karoline Leavitt stated on the social media platform X. “Everybody is aware of what occurs if you drop fourteen 30,000 pound bombs completely on their targets: whole obliteration.”
Nicely … not essentially.
A long time in the past, I lined one other effort to create a strong Earth-penetrating weapon. Within the aftermath of Sept. 11, with a watch towards the caves of Afghanistan, the place Osama bin Laden was believed to be hiding, then-President George W. Bush’s administration checked out whether or not a nuclear weapon may very well be dropped from a airplane into the bottom. The Strong Nuclear Earth Penetrator, because the idea was recognized, would ship a strong shock to underground tunnels and bunkers.
However when scientists acquired concerned, they discovered there was no technique to get a nuclear weapon almost deep sufficient to comprise the blast and radioactive fallout, and this system was finally deserted.
I went again to check out the maths from these early research, and I discovered it truly was pretty easy. The so-called penetration equations have existed because the Nineteen Sixties and rely upon a restricted variety of components, together with the form of the nostril cone, the burden and diameter of the weapon, the velocity at which it hits the bottom, and — crucially — the kind of earth it will get dropped on.
“It relies upon enormously on the form of rock,” says Raymond Jeanloz, a professor on the College of California, Berkeley and one of many unique authors of the 2005 Nationwide Academies Research on earth penetrators.
After I ran the calculations, utilizing a key equation from that research, I discovered that the GBU-57 might go as much as 80 meters (262 ft) underground if it was dropped in silty clay.
In medium-strength rock, issues regarded far totally different. The GBU-57 might solely go round 7.9 meters (about 25 ft) beneath the earth — far wanting the 60 meters claimed by the infographics.
AND MATH!
Plug all of it in, with the coefficient for “Medium-strength rock” and also you get a penetration depth of seven.9 m (25 ft).
That’s WELL wanting the 60 m claimed and the 80-90m depth of Fordow. pic.twitter.com/Ak8lWGfKWk
— Geoff Brumfiel (@gbrumfiel) June 17, 2025
This can be an necessary a part of the explanation the weapon did not destroy its goal — if certainly the bombs did fail because the DIA evaluation claims.
The administration continues to dispute the reporting that the bombs did not hit Fordo, though it has shifted its stance. “The intelligence was very inconclusive. The intelligence says, ‘We do not know, it might have been very extreme’ — that is what the intelligence says,” President Trump advised reporters travelling with him at present within the Hague.
Jeanloz says that it is not simply the energy of the rock. Modifications within the geologic construction also can trigger the bomb to alter path even because it strikes by way of the Earth.
“If there’s any variations … together with fractures or gaps, that may deflect the trajectory into the bottom,” he says. Those self same variations can disperse any blast from the bomb.
It is clear that American planners had been conscious of those sorts of challenges. Quite than dispatching one or two GBU-57s, they despatched 12 to drop on Fordo. Primarily based on satellite tv for pc imagery, it seems to be like they might have been dropped in pairs, with the primary weapon fracturing the rock to extend the penetrating depth of the second. The bombers additionally appeared to focus on Fordo’s air flow system, a potential weak level.
The weapons possible created a strong shockwave within the rock that might have traveled deep underground, rattling the ability under.
However Jeanloz says these shockwaves weaken rapidly as they transfer into the rock. Fordo’s place instantly underneath the ridge of the mountain most likely maximized that safety.
In truth, going deeper is a straightforward resolution to the specter of bunker-busters. A serious conclusion from the 2005 research was that “it is cheaper and simpler for somebody to dig deeper than it’s to penetrate by way of that depth,” he says.
Geology, it seems, might have foiled one of the audacious American air operations in latest reminiscence.
NPR’s Tom Bowman contributed to this report.
