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

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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.