"If there's any variations ... including fractures or gaps, that can deflect the trajectory into the ground," he says. Those same variations can disperse any blast from the bomb.

It's clear that #US planners were aware of these kinds of challenges. Rather than dispatching 1 or 2 GBU-57s, they sent 12 to drop on #Fordow.

The admin continues to dispute the reporting that the bombs failed to hit #Fordow, although it has shifted its stance. "The intelligence was very inconclusive. The intelligence says, 'We don't know, it could have been very severe'—that's what the intelligence says," #Trump told reporters travelling w/him today in the Hague.

Jeanloz says that it's not just the strength of the rock. Changes in the geologic structure can also cause the bomb to change direction even as it moves through the Earth.

Now it appears it may not have. Acc/to a still #classified assessment by the #Defense #Intelligence Agency, the #bombs did not "obliterate" #Iran's #Fordow enrichment site as #Trump initially claimed. Instead, the strike did only limited damage to the advanced centrifuges kept there. At most, the program was set back "a few months," acc/to a US ofcl who confirmed the assessment's existence to NPR but remained anonymous because they were not authorized to speak to press.