Trump says damage to Iran's nuclear sites is 'far below ground level'

“This is a plan that took months and weeks of positioning and preparation so that we could be ready when the President of the United States called,” Defense Secretary Pete Hegseth said during a briefing from the Pentagon.

“It took a great deal of precision. It involved misdirection and the highest of operational security. B-2s went in and out of downtown Tehran -- not Tehran, excuse me -- up these nuclear sites in and out and back without the world knowing at all,“ said Hegseth.

“In that way, it was historic, the strike that included the longest B-2 Spirit bomber mission since 2001. And the first operational employment of the MOP a massive ordinance penetrator mission demonstrated to the world the level of joint and allied integration that speak to the strength of our alliance and our joint forces," said Hegseth.

"As President Trump has stated, the United States does not seek war. But let me be clear, we will act swiftly and decisively when our people, our partners, or our interests are threatened," Hegseth also said.

Defense Secretary Pete Hegseth is briefing reporters on the U.S. strike on Iran, dubbed Operation Midnight Hammer, declaring that “we’ve devastated the Iranian nuclear program” and that Iran’s nuclear program has been “obliterated.”

Hegseth called the military strike “bold and brilliant.”

“When this president speaks, the world should listen,” he said.

Saudi Arabia, Qatar, Iraq and Oman all expressed concern over the U.S. airstrikes on Iranian nuclear sites on Saturday.

Saudi Arabia's Foreign Ministry published a statement noting its "great concern" and expressing the need "to exert all efforts to exercise restraint, de-escalate and avoid escalation" in such "highly sensitive circumstances."

Qatar's Foreign Ministry warned "that the current dangerous tension in the region could lead to catastrophic consequences at both the regional and international levels," while noting its "grave concern" and stressing "the urgent need to halt all military operations and to immediately return to dialogue and diplomatic channels to resolve outstanding issues."

Oman -- which has in the past served as a mediator in talks between Washington and Tehran -- described the American strikes as "illegal aggression" and a "serious violation of international law" in a Foreign Ministry statement posted to X.

Iraqi Foreign Minister Fuad Hussein, meanwhile, said there was a "grave risk posed by attacks targeting religious leaders or nuclear facilities" in Iran, per a readout published on the Foreign Ministry's website.

"Such actions could spark widespread chaos and destabilize the entire region," the readout said, adding that "any strike on Iran's nuclear facilities could lead to a humanitarian and environmental disaster."

Iranian Foreign Minister Abbas Araghchi told reporters in Istanbul, Turkey, on Sunday that President Donald Trump "deceived his own voters" by launching attacks on Iranian nuclear sites, suggesting the president was reneging on his election promise not to get involved in "forever wars."

Araghchi described the American strikes on the Fordow, Natanz and Isfahan sites late Saturday as "outrageous" and laid blame for any fallout on the U.S.

"Washington is solely and fully responsible for the dangerous consequences and far reaching implications of its act of aggression," he said.

Araghchi appeared to close the door on fresh negotiations, saying the path door to diplomacy should always be open but "this is not the case right now."

"It was not Iran, but the U.S. who betrayed diplomacy," Araghchi said. "They betrayed negotiations."

-ABC News' Victoria Beaule