U.S. intelligence assessments indicate that the estimated interval Iran would require to produce a nuclear weapon has stayed essentially unchanged since last summer, when analysts judged that a U.S.-Israeli operation had pushed the timeline out to roughly nine months to a year, according to three people familiar with the matter.
Those evaluations remain broadly stable even after nearly two months of conflict that U.S. President Donald Trump said he launched in part to prevent the Islamic Republic from obtaining a bomb. The most recent U.S. and Israeli strikes, which began on February 28, have been aimed largely at conventional military capabilities, though Israel has struck a number of significant nuclear-related sites.
Analysts and officials told reporters that the persistence of the earlier estimate suggests that substantially hindering Iran’s nuclear progress may require the physical destruction or removal of Iran’s remaining inventory of highly enriched uranium, commonly abbreviated as HEU. The assessments reflect the difficulty of significantly degrading a program when much of the fissile material remains intact.
Conflict has been in a relative lull since the United States and Iran agreed to a truce on April 7 and pledged to pursue talks toward a peaceful settlement. But tensions remain elevated. Iran’s disruption of traffic through the Strait of Hormuz has choked off about 20% of global oil flows, contributing to a worldwide energy crunch, officials said.
Defense Secretary Pete Hegseth has publicly said that the United States seeks to ensure Iran does not acquire a nuclear weapon through ongoing negotiations, a priority reiterated by senior U.S. officials.
U.S. intelligence agencies had assessed that prior to the 12-day series of strikes last June, Iran could likely produce enough weapons-grade uranium and assemble a bomb in roughly three to six months, two of the sources said. After those June attacks - which struck the Natanz, Fordow and Isfahan nuclear sites - U.S. estimates were revised to place the timeline nearer to nine months to a year, according to two of the people and another person familiar with the assessments.
Those June operations destroyed or severely damaged the three enrichment facilities that were known to be operational at the time. Yet the U.N. nuclear watchdog has been unable to account for roughly 440 kilograms of uranium enriched to 60 percent. Inspectors believe about half of that material was stored in an underground tunnel complex at the Isfahan Nuclear Research Center, but they have been unable to confirm its status because inspections are suspended.
The International Atomic Energy Agency has assessed that the total HEU stockpile would be enough, if further enriched, to produce about 10 nuclear devices.
White House spokeswoman Olivia Wales characterized the combined military efforts this year and last summer as complementary operations. She said the June strikes and the later campaign together destroyed critical components of Iran’s nuclear and defense-industrial capabilities, and reiterated a presidential commitment that Iran must not obtain a nuclear weapon. "President Trump has long been clear that Iran can never have a nuclear weapon - and he does not bluff," she said.
The Office of the Director of National Intelligence did not respond to a request for comment.
U.S. officials have consistently framed stopping Tehran’s nuclear program as an essential objective of military and diplomatic efforts. Vice President JD Vance reiterated that stance on social media on March 2, writing that preventing Iran from obtaining a nuclear weapon is the goal of the operation.
Analysts said the steady estimate of the time Iran would need to build a weapon reflects the focus of the most recent U.S. and Israeli military campaign. While Israel has struck several nuclear-related targets, including a uranium-processing facility in late March, U.S. strikes have centered on conventional military targets, Iranian leaders, and the country’s military-industrial base.
Some analysts noted that the lack of a clear change in the timeline may also be explained by the scarcity of major nuclear targets that can be safely and effectively neutralized after last summer’s strikes had already hit the known enrichment sites.
Eric Brewer, a former senior U.S. intelligence analyst who once led assessments of Iran’s nuclear program, said it was not unexpected that the official timelines did not move appreciably. "Iran still possesses all of its nuclear material, as far as we know," Brewer said. He added that much of that material is likely stored in deeply buried underground facilities that current U.S. munitions cannot penetrate.
In recent weeks, U.S. officials have considered more hazardous operations to further hinder Tehran’s nuclear progress. Options under discussion have included ground raids to recover the HEU believed to be held in the tunnel complex at the Isfahan site, according to the people familiar with the intelligence.
Iran has repeatedly denied that it is pursuing nuclear weapons. U.S. intelligence agencies and the IAEA have said Tehran halted a warhead development effort in 2003, but some experts and Israeli officials assert that Iran retained significant elements of the program in secret.
Evaluating Iran’s nuclear capacity precisely remains a difficult task even for the world’s most proficient intelligence services, experts say. Multiple U.S. agencies have conducted separate studies of the program, and while there is a broad consensus about Tehran’s capacity to build a weapon, the sources noted that divergent assessments do exist.
It remains possible that Iran’s nuclear timeline has been set back further than the formal intelligence estimates indicate. Some U.S. officials, including Secretary of State Marco Rubio, have argued that strikes against Iranian air defenses reduced the nuclear threat by weakening Iran’s ability to protect its nuclear sites should it attempt to accelerate weapons production in the future.
Another factor that officials and analysts say has introduced uncertainty is the reported assassinations of several of Iran’s top nuclear scientists by Israeli operatives. David Albright, a former U.N. nuclear inspector who now directs the Institute for Science and International Security, said those killings have injected significant doubt about Tehran’s ability to construct a functional weapon. "I think everyone agrees knowledge can't be bombed, but know-how certainly can be destroyed," Albright said.
While U.S. assessments currently indicate no material shortening of the timeline for a weapons-capable Iran compared with last summer’s estimate, the sources emphasized the overall uncertainty surrounding the program and the limited visibility inspectors and analysts have without full access to sites and materials.
Officials continue to weigh the risks and benefits of different courses of action - from further strikes on infrastructure to potential retrieval operations - recognizing that moving beyond the present estimates would likely require addressing the location and status of Iran’s remaining HEU.