The US military did not use bunker-buster bombs on one of Iran’s largest nuclear sites last weekend because the site is so deep that the bombs likely would not have been effective, the US’ top general told senators during a briefing on Thursday.
The comment by Joint Chiefs of Staff Chairman Gen. Dan Caine, which was described by three people who heard his remarks and a fourth who was briefed on them, is the first known explanation given for why the US military did not use the Massive Ordnance Penetrator bomb against the Isfahan site in central Iran. US officials believe Isfahan’s underground structures housenearly 60% of Iran’s enriched uranium stockpile, which Iran would need in order to ever produce a nuclear weapon.
US B2 bombers dropped over a dozen bunker-buster bombs on Iran’s Fordow and Natanz nuclear sites. But Isfahan was only struck by Tomahawk missiles launched from a US submarine.
The classified briefing to lawmakers was conducted by Caine, Defense Secretary Pete Hegseth, Secretary of State Marco Rubio and CIA Director John Ratcliffe. Spokespeople for Caine did not return requests for comment.
Democratic Sen. Chris Murphy told CNN on Thursday night after receiving the briefing that some of Iran’s capabilities “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.”
An early assessment produced by the Defense Intelligence Agency in the day after the US strikes said the attackdid not destroy the core componentsof the country’s nuclear program, including its enriched uranium, and likely only set the program back by months, CNN has reported. It also said Iran may have moved some of the enriched uranium out of the sites before they were attacked.
The Trump officials who briefed lawmakers this week sidestepped questions about the whereabouts of Iran’s stockpile of already-enriched uranium. President Donald Trump again claimed Friday that nothing was moved from the three Iranian sites before the US military operation.
But Republican lawmakers emerged from the classified briefings on Thursday acknowledging that the US military strikes may not have eliminated all of Iran’s nuclear materials. But they argued that doing so was not part of the military’s mission.
“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 told 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.”
“The purpose of the mission was to eliminate certain particular aspects of their nuclear program. Those were eliminated. To get rid of the nuclear material was not part of the mission,” GOP Rep. Greg Murphy told CNN.
“Here’s where we’re at: the program was obliterated at those three sites. But they still have ambitions,” said Republican Sen. Lindsey Graham of South Carolina. “I don’t know where the 900 pounds of highly enriched uranium exists. But it wasn’t part of the targets there.”
“(The sites) were obliterated. Nobody can use them anytime soon,” Graham also said.
Weapons expert and professor at the Middlebury Institute of International Studies Jeffrey Lewis told CNN that commercial satellite images show that Iran has accessed the tunnels at Isfahan.
“There were a moderate number of vehicles present at Isfahan on June 26 and at least one of the tunnel entrances was cleared of obstructions by mid-morning June 27,” Lewis said. “If Iran’s stockpile of (highly enriched uranium) was still in the tunnel when Iran sealed the entrances, it may be elsewhere now.”
Additional satellite imagery captured on June 27 by Planet Labs show the entrance to the tunnels were open at the time, according to Lewis.
The preliminary DIA assessment noted that the nuclear sites’ above ground structures were moderately to severely damaged, CNN has reported. That damage could make it a lot harder for Iran to access any enriched uranium that does remain underground, sources said, something that Graham alluded to on Thursday.
“These strikes did a lot of damage to those three facilities,” Murphy, the Connecticut Democrat, told CNN on Thursday night. “But Iran still has the know-how to put back together a nuclear program. And if they still have that enriched material, and if they still have centrifuges, and if they still have the capability to very quickly move those centrifuges into what we call a cascade, we have not set back that program by years. We have set it back by months.”
Caine and Hegseth on Thursday said the military operation against Fordow went exactly as planned but did not mention the impacts to Isfahan and Natanz.
CNN’s Manu Raju contributed to this report.