Bunker-buster bombs ‘ineffective’ against Iran's Isfahan nuclear facility; Top US general reveals why

The U.S. military deliberately avoided using bunker-buster bombs on Iran’s Isfahan nuclear complex because the site’s extreme depth rendered the weapons ineffective, Joint Chiefs Chair Gen. Dan Caine confirmed in a classified Senate briefing. Isfahan’s underground facilities reportedly store 60% of Iran’s enriched uranium, critical for bomb development, buried beyond the reach of America’s GBU-57 Massive Ordnance Penetrators (MOPs). Instead, submarines launched Tomahawk missiles to strike surface structures. The disclosure, first reported by CNN, underscores tactical limitations against Iran’s fortified sites. While B-2 stealth bombers dropped 14 bunker-busters on the shallower Fordow and Natanz facilities, Isfahan’s geology demanded alternative tactics. CIA Director John Ratcliffe noted that most of Iran’s nuclear material remains concentrated at Isfahan and Fordow, amplifying strategic concerns about untouched uranium reserves.

Differences of opinion between claims

The decision highlights a stark gap between military capabilities and presidential rhetoric. Despite President Trump’s claims that strikes "obliterated" Iran’s nuclear program, an early Defense Intelligence Agency (DIA) assessment concluded core facilities survived, setting back enrichment only "by months."

Satellite imagery analyzed by weapons expert Jeffrey Lewis showed vehicles near Isfahan’s tunnels days before the strike, with entrances reopened by June 27, suggesting uranium may have been moved. Technical analyses further indicate bunker-busters would have failed: Fordow’s 90-meter depth exceeds the MOP’s 25-meter penetration in medium-strength rock. At Isfahan, even 30,000-pound bombs couldn’t reach chambers housing centrifuges. "Annihilated is too strong," conceded IAEA chief Rafael Grossi, though he acknowledged "enormous damage" to above-ground infrastructure.

Democratic Sen. Chris Murphy told CNN on Thursday night, after receiving the briefing, that some of Iran’s facilities “are so far underground that we can never reach them. So they have the ability to move a lot of what has been saved into areas where there’s no American bombing capacity that can reach it.”

Intel disputes obliteration claims as satellite data hints at relocated materials
 

Republican lawmakers emerged from briefings acknowledging uranium stocks likely endure but defended the mission’s scope. “There is enriched uranium in the facilities that moves around, but that was not the intent or the mission,” Republican Rep. Michael McCaul of Texas was quoted as telling CNN. “My understanding is most of it’s still there. So we need a full accounting. That’s why Iran has to come to the table directly with us, so the (International Atomic Energy Agency) can account for every ounce of enriched uranium that’s there. I don’t think it’s going out of the country, I think it’s at the facilities,” McCaul continued.

However, White House assertions clash with intelligence: Trump insisted "nothing was moved" pre-strike, despite DIA evidence of relocations and Israel’s assessment of a "significant hit" (not total destruction).

With Tehran now suspending IAEA access, confirming uranium’s status remains impossible, leaving a critical void in assessing the operation’s true impact.