Defence Secretary Pete Hegseth on Thursday said US strikes on Iranian nuclear sites had been "a resounding success”, angrily pushing back against the “fake news” media for questioning how effective the attacks were.
President Donald Trump and his administration are furious after a preliminary assessment suggested the attacks may not have fully destroyed Iran’s nuclear facilities. The report was leaked to the press.
“President Trump directed the most complex and secretive military operation in history," Mr Hegseth told the press at the Pentagon. "And it was a resounding success, resulting in a ceasefire agreement and the end of the 12-day war."
Gen Dan Caine, US Chairman of the Joint Chiefs of Staff, told the press conference that experts had spent 15 years developing the technology to attack Fordow and other Iranian nuclear bases.
He said the GBU-57, the 13.6-tonne munition dropped from B-2 stealth bombers on Saturday, was designed to burrow into the Fordow site and explode when deep underground.
Experts “accomplished hundreds of test shots and dropped many full-scale weapons against extremely realistic targets for a single purpose – kill this target at the time and place of our nation's choosing”, Gen Caine said.
The bombs do not leave a large crater as they explode far below the surface, he said, noting the weapons had flown down three ventilation shafts and all exploded as planned.
Mr Hegseth lambasted the Pentagon press corps for reporting on the initial assessment that suggested the US strikes on Fordow might not have fully "obliterated" Fordow.
“It’s like in your DNA and in your blood to cheer against Trump,” he said. “It's almost personal when we see the way in which leaks are used to try to disparage the outcome or muddy the waters about the impact of what happened.”
He said that during the early stages of the bomb's development, the military had so many experts working on the programme doing modelling and simulation "that we were quietly and in a secret way, the biggest users of supercomputer hours within the United States of America".
The pilots of the bombers involved in the weekend strikes described the flash after the bomb drop as “the brightest explosion they had ever seen”, Gen Caine said.

A convoy of lorries photographed outside Fordow ahead of the strikes has led to speculation some of the enriched uranium was moved to another site before it could be destroyed.
Asked whether this was the case, Mr Hegseth acknowledged that the Pentagon was "looking at all aspects of intelligence and making sure we have a sense of what was where.
"I'm not aware of any intelligence that says things were not where they were supposed to be,” or that they were moved, Mr Hegseth said.
President Trump later said on Truth Social that the vehicles "at the site were those of concrete workers trying to cover up the top of the shafts".
"Nothing was taken out of facility. Would take too long, too dangerous, and very heavy and hard to move!" he wrote.
Gen Caine also described how US troops at Al Udeid Airbase had defended against an Iranian missile attack on Monday.
He said about 44 American service members responsible for defending the entire base were present as rounds of Patriot missiles were launched.
Gen Caine said Qatar joined in the successful defence of what he called the largest single Patriot engagement in US military history.