It’s an issue that won’t go away. Despite the U.S. raids on Iranian nuclear facilities being two weeks in the past, the controversy over their effect continues to be publicly debated. A leaked preliminary Defense Intelligence Agency assessment indicated that Iran’s nuclear program was set back by only several months, while President Trump claimed the facilities have been “obliterated.”
Much of this confusion arises from commentators answering different questions and the answers then being applied to the wrong question. For example, the question of how long it will take to rebuild the Iranian nuclear program is different from the question of how long until Iran could have a nuclear weapon. The discussion below disentangles the five key questions about the status of the Iranian nuclear program.
Q1: Was the U.S. military strike a great technical achievement?
A1: Yes, without question. The strikes were a carefully choreographed and masterfully executed operation: seven B-2 bombers flew 36 hours round-trip and dropped fourteen 30,000-pound bombs with precision against targets at Natanz and Fordow, “half the size of a refrigerator door.” At the same time, an Ohio-class submarine launched two dozen Tomahawk land-attack cruise missiles against the Isfahan site.
The technical aspects of the operation were stunning, maybe not the “most complex and secretive military operation in history”—the D-Day landings in Normandy come to mind—but remarkable, nevertheless. Only the United States could execute such a mission.
However, in bombing, as in life, a perfectly executed plan does not necessarily lead to the desired outcome, and asking questions about the outcome does not diminish the skill or courage of the service members involved.
Q2: How much damage did the U.S. and Israeli air campaign do to Iran’s nuclear weapons program?
A2: The damage was significant if measured by physical destruction and how long it would take to get the nuclear program back to where it was before the attacks.
Most of that damage came from Israel’s 12-day campaign against the Iranian nuclear program. The above-ground enrichment facility at Natanz and facilities to weaponize nuclear materials at Isfahan were hit from the outset. The Israeli air strikes also damaged a nuclear reactor under construction and university buildings associated with nuclear programs. The U.S. “bunker buster” bombs sought to reach underground facilities at Natanz and Fordow, while the Tomahawks collapsed the access tunnels to buried facilities in Isfahan.
Targets included conventional military sites as well. Israeli missiles struck Iranian missile storage sites and major airbases. At the same time, commando units destroyed Iranian air defense and missile systems using drones from smuggled trucks and a covert base inside Iran.
The campaign also involved a partial decapitation of Iran’s military and nuclear organizations, with more than two dozen military commanders and nuclear scientists killed. Iran lost generals on top of its military chain of command, including the highest-ranked commander after Ayatollah Ali Khamenei. The Israeli attack also wiped out the senior leadership of drone and air defense forces. Among the dead scientists was Fereydoon Abbasi-Devani, the former head of the Atomic Energy Organization of Iran, who survived a 2010 Israeli assassination attempt.
The International Atomic Energy Agency chief, Rafael Grossi, suggested Iran could have “a few cascades of centrifuges spinning and producing enriched uranium” in months, referring to a series of centrifuges connected in sequence to enrich uranium to a level that a single machine cannot attain.
As of May, Iran had been operating over a hundred cascades, each comprising around 160–180 centrifuges, depending on their type. These machines are vulnerable to vibrations, and Grossi assessed that most, if not all, of Iran’s centrifuges suffered “significant physical damage” from the airstrikes. It may be possible that Iran soon restores a “few” cascades, but restoring enrichment facilities to prewar levels will take a large amount of time and resources.
Further, resuming uranium enrichment is not enough. Producing a nuclear weapon also requires a functioning network of nuclear laboratories, weapons manufacturing facilities, testing capacity, and educational programs. Each element of the network must now be rebuilt.
Q3: How effective were the U.S. airstrikes?
A3: Although the damage to above-ground facilities is clear and relatively easy to assess, assessing damage to underground facilities must be speculative.
Satellite imagery showing debris patterns, bomb craters, and recovery vehicles in the aftermath can provide some clues. Classified models built on more than a decade of work studying Fordow and Natanz likely offer more understanding. However, conclusions are hard to draw this soon, especially with limited access to the sites. Assessments of the U.S. strike consequently have ranged from Secretary of Defense Pete Hegseth’s confidence—“decimating . . . obliterating, destroying” Iran’s nuclear program—to the leaked preliminary report by the Defense Intelligence Agency suggesting Iran could have a nuclear weapon in nine months.
The strikes on Isfahan with Tomahawk missiles, a tenth of the mass of the ground-penetrating bombs used on Fordow and Natanz, are raising more questions. Satellite imagery analysis has suggested that the Iranian may have been able to repair the collapsed tunnels, potentially allowing them to recover any enriched uranium stored underground. On the other hand, Iran could be conducting a deception, aware that analysts are keenly monitoring the sites.
Moreover, measuring the effects of bombing campaigns is rarely straightforward. While bombs may hit their targets as planned, adversaries may quickly adapt to mitigate the physical effects of the impact. On the other hand, our colleague Eliot Cohen, who had led the post–Desert Storm airpower assessment, wrote about the importance of secondary effects. Thus, even if the intended damage is not achieved, the psychological effects of overwhelming firepower delivered precisely over long distances might debilitate decisionmaking or trigger cascading panic.
Q4: Does Iran retain enough residual enrichment and assembly capability to produce a nuclear weapon?
A4: This timeline would be shorter than for reconstituting the whole program. Major unknowns are the fate of Iran’s existing stockpile of 400 kilograms of 60 percent enriched uranium, how badly damaged the centrifuges were, and how much equipment was moved before the bombing.
James Acton, a nuclear policy expert at Carnegie Institute, and Jeffrey Lewis, an arms control expert at Middlebury Institute of International Studies, argue that Iran suffered serious losses but retains enough capability to build a weapon in a year. They estimate that Iran could restart its surviving centrifuges, build new centrifuges, bring into operation an additional, undeclared facility, and use the enriched uranium it has already produced.
Israel disagrees, and they have so thoroughly penetrated Iranian military and political institutions that their views must be taken seriously. Israel’s Atomic Energy Commission reported that Iran’s ability to develop nuclear weapons has been set back “many years,” an assessment also reportedly shared by CIA Director John Ratcliffe.
A fast path requires a lot of things to go right for Iran, but it cannot be ruled out. This assumes, of course, no further airstrikes.
Q5: Could Iran rebuild its program along some timeline, whether months, years, or decades?
A5: Yes, the technical knowledge does not go away, and although Iran has lost many top scientists and officials, those could be replaced over time. However, nuclear weapons development is not just a matter of technical competence but also political decisionmaking. The question, then, is whether Iran wants to rebuild, given the need to divert billions of dollars from a struggling economy. The fact that Iran is clearing the rubble does not indicate a decision to rebuild the program. Our colleague Dan Byman discussed the uncertain long-term consequences of strikes on Iran in this commentary.
The psychological effects of the 12-day campaign—Iran’s powerlessness, Israeli resourcefulness, and U.S. global reach—will further impede Iran’s efforts to rebuild its nuclear program. Israel’s assassinations of top scientists could deter remaining Iranian nuclear experts from working openly out of fear of becoming the next target. Rebuilding trust after demonstrated Israeli penetration of the Iranian national security establishment will complicate recruiting new talent for a clandestine nuclear program.
The strikes have also set an important precedent that the United States and Israel will take direct military action against Iran’s nuclear program. U.S. and Israeli leaders may now feel even less politically inhibited in launching future attacks. Militarily, Iranian facilities will be vulnerable for many years since Israel degraded Iran’s air defenses, and the United States destroyed much of what remained. Our colleagues Kari Bingen and Clayton Swope suggest these points.
History offers some guides about what might happen next. After Israel bombed an Iraqi nuclear reactor, Iraq tried to continue its program covertly, but that proved extremely difficult. In 2007, Israel bombed a nuclear reactor in Syria that the North Koreans had helped develop. That effort was not reconstituted.
With time, the key questions about damage and rebuilding will have answers. The pressing near-term decisions are about negotiations and additional air strikes. Given the consensus that Iran has experienced at least some delay in its nuclear weapons program, there is no need for an immediate restrike. The United States and Israel can let negotiations run their course. Those negotiations may find some common ground, perhaps a nuclear program operated within certain parameters and under an inspection regime. If not, then a “12-day war 2.0” is likely.
Mark F. Cancian (colonel, U.S. Marine Corps Reserve, ret.) is a senior adviser with the Defense and Security Department at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Chris H. Park is a research associate for the Arleigh A. Burke Chair at CSIS.
