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

Iranian Foreign Minister Abbas Araghchi, speaking in English at the Organization of Islamic Cooperation in Istanbul, called the American strikes in Iran "outrageous" and laid blame on the U.S. for any fallout.

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

He for now appeared to close the door on diplomacy, saying the 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. They betrayed negotiations.” he said, denouncing Israel and the U.S. for attacking Iran amid diplomatic talks.

Araghchi also said Trump betrayed his election promise not to get involved in "forever wars," saying Trump "deceived his own voters" by joining Israel in attacking Iran.

-ABC News' Victoria Beaule

Hegseth said there were public and private messages being directly delivered to the Iranians prior to the attack through multiple channels, “giving them every opportunity to come to the table.”

“They understand precisely what the American position is, precisely what steps they can take to allow for peace, and we hope they do so,” he said.

He also said the operation is not open-ended and is not about “regime change.”

“Well, anything can happen in conflict. We acknowledge that, but the scope of this was intentionally limited,” Hegseth said.

According to Caine, troops in the region were not given an advance warning of the attacks.

Lawmakers were notified immediately after the strike, according to the briefing.

“I know that battle damage is of great interest. Final battle damage will take some time, but initial battle damage assessments indicate that all three sites sustained extremely severe damage and destruction,” said Caine.

Later, Hegseth added that “The battle damage assessment is ongoing, but our initial assessment, as the chairman said, is that all of our precision munitions struck where we wanted them to strike and had the desired effect, which means especially the primary target here, we believe we achieved destruction of capabilities there.”

Joint Chiefs Chairman Gen. Dan Caine told reporters the mission was a “complex and high-risk mission” that was known to only a few people and relied on decoys to protect the integrity of the mission.

The B2 bombers deployed shortly after midnight on what would become the longest flight involving the B2 fleet since 2001, Caine said. A total of 14 bunker buster bombs known as MOPS were dropped, with the first two dropped at 2 a.m.

The attack also involved a U.S. submarine that launched more than two dozen Tomahawk land attack cruise missiles surface targets, according to Caine.

“This was a complex and high risk mission carried out with exceptional skill and discipline by our joint force," he said.

Iran did not deploy fighters or surface to air missiles during the mission, Caine said: “Throughout the mission, we maintained the element of surprise."

It was also the first use of the massive ordnance penetrator, or MOP, which had only been used in a testing role, according to Caine.