President Donald Trump has proclaimed that the U.S. bombing of Iranian nuclear enrichment facilities was an unmitigated success.
"The sites that we hit in Iran were totally destroyed, and everyone knows it," he wrote in a social media post Monday.
U.S. strikes on Iran may have been a tactical win, with all three targets hit and all planes safely returned home. But defense officials and nuclear experts are still trying to determine whether they achieved their stated strategic goal of eliminating Iran's nuclear program, even as Trump declared late Monday afternoon that Iran and Israel had agreed to end their war.
"Final battle damage will take some time, but initial battle damage assessments indicate that all three sites sustained extremely severe damage and destruction," Gen. Dan Caine, chairman of the Joint Chiefs of Staff, said in a Sunday morning Pentagon briefing.
Under Defense Department guidelines, it could take days or even weeks for the U.S. military to complete a formal battle damage assessment, or BDA, primarily by using overhead surveillance to gather information from the sites of the blasts. But experts caution there are limits to what information can be gathered.
Hearing directly from Iranians discussing the damage, either through human intelligence gathered by sources in Tehran's government or electronic interception of those conversations, would be among the best ways to assess the effects, although they are also among the most difficult methods.
"In lieu of highly vetted source intelligence, there is no real way to conduct any thorough" BDA," said Wes Bryant, who served as a targeter in Air Force Special Operations.
The thousands of sophisticated uranium enrichment centrifuges at the underground Fordow site were probably significantly damaged, even if they were not directly hit, given the use of deep-penetration bombs and the "extreme vibration-sensitive nature of the centrifuges," Rafael Grossi, director general of the International Atomic Energy Agency, told IAEA governors at an emergency meeting Monday in Vienna.
But "at this time, no one -- including the IAEA -- is in a position to have fully assessed the underground damage" at Fordow, Grossi said. The agency won't know, he added, until its inspectors still in Iran are able to return to the facility.
More important is what happened to the more than 900 pounds of uranium the IAEA says Iran has already enriched to near-weapons grade, enough to make more than a dozen bombs. Some was stored at an underground site near Isfahan, according to the IAEA, which was hit with submarine-launched U.S. cruise missiles.
"Why am I not impressed?" Jeffrey Lewis, a nuclear and nonproliferation expert at the Middlebury Institute of International Studies, wrote in a lengthy post on X. The enriched uranium "was largely stored in underground tunnels. ... Despite extensive Israeli and US attacks [on] the facility, there does not seem to have been any effort to destroy these tunnels or the material that was in them."
Earlier IAEA reports indicated that some of the enriched material may have been moved to other, undeclared locations. Iran is also believed to have additional equipment, outside of the bombed Isfahan conversion site, to convert enriched uranium hexafluoride gas into metal that can be used for constructing nuclear weapons.
Iran has dozens of sites associated with its nuclear program, which it has insisted is only for peaceful and civilian activities such as power generation and research. The day before Israel started its attacks earlier this month, the government in Tehran said that it had constructed a new facility outside of Natanz that could be used to build new centrifuges. That site is even deeper underground than the enrichment facility at Fordow, built a few hundred feet into a mountain and thought to be the limit of what U.S. "bunker buster" bombs could reach.
"The point is they have material that they have made at other facilities," Lewis said in an interview. "We don't know what became of that."
Lewis and others suggested that the United States was aware of the limitations of a military attack on the widespread Iranian nuclear program and was more interested in showing Tehran that Washington was prepared to use force to stop it.
"It is a loss for the Iranians," Lewis said of the destruction at Fordow, Isfahan and Natanz, "but it is not anything like the scale of the attack you would mount if the goal was really to eliminate the program.
"This problem has delayed them, and undoubtedly there must be things that have been destroyed that they now have to reconstitute," he said, "but the rebuilding could probably be done in no more than a year."
Israeli Prime Minister Benjamin Netanyahu said over the weekend that Iran's nuclear program, thought to be months or a year from producing an actual nuclear weapon, had now been set back two or three years.
Trump said in the immediate aftermath of the strikes that they had completely "obliterated" Iran's program, a word also used by Defense Secretary Pete Hegseth. Vice President JD Vance told NBC's Meet the Press that "we destroyed the Iranian nuclear program."
Later in the same interview, Vance tempered his assessment, saying he was "not going to get into sensitive intelligence about what we've seen on the ground there in Iran. But we've seen a lot and I feel very confident that we've substantially delayed their development of a nuclear weapon."
Speaking to Fox News on Monday evening after Trump's ceasefire announcement, Vance repeated that Iran's nuclear program had been completely destroyed and was no longer capable of producing a nuclear weapon.
However the White House decides to measure success, the military -- always a stickler for procedure -- has a detailed system for an official battle damage assessment.
"I think the BDA is still pending, and it would be way too early for me to comment on what may or may not still be there," Caine said Sunday.
Gauging the effect of strikes is often done with surface imaging from satellites, drones or aircraft that can help analysts determine to what degree enemy equipment and facilities were affected by attacks. That task is much more challenging when the targets are subterranean and deep inside hostile territory. The bombs dropped on the Fordow site burrowed through mountainside and exploded on a delayed timer, collapsing dirt and rock that conceal the full extent of the damage.
One technology known as LIDAR, for "light detection and ranging," can help produce three-dimensional maps of an environment by measuring the time it takes laser pulses to return to a sensor affixed to an aircraft or drone. It has been used to peer through foliage and reveal ruins in the Amazon.
In the case of Fordow, a high-altitude surveillance aircraft with the technology can help analysts review ground disturbances and subtle terrain changes. "The composition of dust and debris ejected from the munition entry points and material that rushed out of the earth beneath them may also provide clues to the impacts," said Bryant, the Air Force targeter.
Terrain modeling software can also help predict the scale of damage by feeding information about the munitions used, rock and soil composition and what is known about the structures, he said, although those estimates can be imperfect.
Complicating the effort is the lack of precedent: the strikes on Iran's nuclear facilities marked the first wartime use of the 30,000-pound Massive Ordnance Penetrator munition. The focus on targeting enemy structures underground is a relatively new Pentagon initiative, with several offices across the Defense Department taking interest in the capability.
One corner of that effort, the Hard Target Research and Analysis Center, was created in the months after the Sept. 11 attacks, as al-Qaeda militants took refuge in caves and tunnels in Afghanistan. The work has taken on new importance with adversaries such as China and North Korea turning to subsurface facilities to protect against bombs and surveillance. Underground infrastructure used by Hamas in Gaza may also be adopted by other militant groups.
A senior Israeli official said in the aftermath of the U.S. attack that his government's hope is that the threat of additional U.S. involvement will lead Tehran to negotiate an deal to fully denuclearize.
Regardless of a possible ceasefire, "if the Iranian regime decides to go on without an agreement and to try to rebuild again," the official said, speaking on condition of anonymity to discuss ongoing operations,"they should understand that it won't be a huge challenge for us to get there again and destroy it again."