Why America's giant bunker-busting bombs may have failed to reach their target, NPR, June 25

[progree]

The infographics were everywhere in the run-up to Sunday's early-morning strike on Iran's nuclear facilities by American stealth bombers.

They depicted America's bunker-busting bomb, (snip). the graphics showed it plowing a narrow channel deep beneath the ground — around 60 meters, or 200 feet — and erupting in an illustrated explosion.

(snip)

I went back to take a look at the math from those early studies, and I found it actually was fairly straightforward. The so-called penetration equations have existed since the 1960s . . .

"It depends enormously on the kind of rock," (snip)

When I ran the calculations, using a key equation from that study, I found out that the GBU-57 could go up to 80 meters (262 feet) underground if it was dropped in silty clay.

In medium-strength rock, things looked far different. The GBU-57 could only go around 7.9 meters (about 25 feet) beneath the earth — far short of the 60 meters claimed by the infographics.

More: https://www.mprnews.org/story/2025/06/25/npr-did-america-bunker-busting-bombs-fail-reach-iran-nuclear-target

As an interesting sidelight, back in the Osama Bin Laden Tora Bora days, the U.S. looked at the feasibility of a nuclear bunker buster and scientists found there was no way to get a nuclear weapon nearly deep enough to contain the blast and radioactive fallout, and the program was eventually abandoned.

[John1956PA]

1. Of course. Mother nature's strength and immensity dwarf humans' silver bullets.

The energy of a bomb is intense in the atmosphere, but it is handily absorbed by rock strata. The power of a bunker buster wanes when it is absorbed by millions of cubic feet of rock near the surface.

Likewise, the scope and energy of an ocean storm dwarfs that of a nuclear bomb. Trump does not understand the basics of science. Grade school classes teach that there is more kinetic energy in a bathtub of tepid water than there is in a red-hot nail. The energy of a nuclear bomb detonated in an ocean storm (as Trump suggested) would be minuscule compared to the power of the storm which covers millions of square miles.

[LetMyPeopleVote]

2. Geology as warfare: Iran put its missiles where physics, not diplomacy, keeps them safe

CNN satellite analysis and Alma Research findings show Iran’s underground tunnel cities, with internal rail systems that move missiles to blast-door exits, have survived the bombing campaign largely intact. The geology, analysts say, is the real defense.

Link to tweet

https://www.thestatesman.com/world/iran-underground-missile-railway-tunnel-us-israel-strikes-operation-epic-fury-1503573121.html

Three weeks of intensive US and Israeli strikes on Iran’s ballistic missile infrastructure have destroyed radar systems, collapsed tunnel entrances, and cratered ventilation shafts across dozens of sites. Iran keeps firing. The reason, according to satellite analysis by CNN and assessments by Israeli security research centre Alma Research, lies not above the ground but hundreds of metres beneath it; inside a network of underground missile cities connected by internal railways, carved into mountains that no bomb in the current American or Israeli arsenal can fully reach.

Iran’s underground missile programme is not a recent improvisation. Reports that emerged as far back as 2020 claimed an automated railway system running through cavernous tunnels, transporting ballistic missiles between assembly halls, storage vaults, and blast-door exits. What is becoming clearer now, as Operation Epic Fury enters its fourth week, is the scale of what was built and the limits of what air power alone can do against it.....

The central constraint is geological, and it has now been publicly stated by Iran itself. Former IRGC Aerospace Force commander Brigadier General Amir Ali Hajizadeh said that Iran built its missile bases across provinces and cities at a depth of 500 metres.

The most powerful weapon the United States has for destroying hardened underground targets is the GBU-57 Massive Ordnance Penetrator – a 30,000-pound bomb built specifically for this purpose. It can penetrate “approximately 60 metres of reinforced concrete or roughly 40 metres of moderate rock. Granite is harder than moderate rock. Five hundred metres is more than twelve times the weapon’s maximum penetration depth. The gap between the bomb and the tunnel is not a margin of error.”....

“IRGC did not prepare for this war by building rockets. It prepared by building railways inside mountains. The rockets are replaceable. The railways are permanent. And the granite that protects them was formed before mammals existed. The strait is 21 miles wide. The mountain is 500 metres deep. And the railway inside it is still delivering missiles to the surface,” he added.

Link to tweet

Iran has continued to fire ballistic missiles throughout Operation Epic Fury, including the attempted strike on the joint US-UK base at Diego Garcia. Trump has said the operation is running weeks ahead of schedule and that Iran’s military is finished. The satellite imagery and the institutional assessments tell a more complicated story: one in which the visible war, fought above ground, has made genuine progress, and the invisible war, fought half a kilometre underground, has barely begun.

There is a reason why only one-third of Iran's missiles have been destroyed. Iran has been preparing for these attacks for decades. Iran's missile facilities are beyond reach of bunker buster bombs and there is no practical way without a very large number of troops to take out these missies.

[LetMyPeopleVote]

3. This is Iran's version of the US NORAD Cheyenne Mountain Complex (CMOC)!

Link to tweet

Update: B-52 stealth bombers have used bunker busters bombs to strike Iran’s main underground complex, but can’t penetrate’ Iran 1,444ft-deep missile storage and subway system!

This is Iran’s version of the US NORAD Cheyenne Mountain Complex (CMOC)! A massive underground military facility built inside a Mountain! Made of solid Granite, the mountain dead zone is higher than Empire State Building!

The US will have to send troops to secure or destroy the complex!!