Tehran has been targeted by the United States and Israel since February 28, with the justification that Iran must not be allowed to use its uranium to develop a nuclear bomb. After former U.S. President Donald Trump withdrew from the nuclear agreement with Iran eight years ago, Tehran accumulated approximately 22,000 pounds, or nearly 11 tons, of enriched uranium. Even after nearly two months since the attacks began, it remains unclear where this vast stockpile is currently located. However, the head of the United Nations nuclear agency, Rafael Grossi, has indicated that a significant portion of Iran’s highly enriched uranium is likely stored at the Isfahan Nuclear Technology Center. Reports from international media have explored how Iran accumulated such a large quantity of uranium and where it might now be.
The higher uranium is enriched, the easier it becomes to further increase its enrichment level—while reaching 20 percent from zero is difficult, moving from 20 percent to 60 or even 90 percent is comparatively easier. Uranium enriched to 90 percent is typically used for nuclear weapons. Iran began industrial-scale uranium enrichment in 2006, claiming peaceful intentions. In 2010, it announced enrichment up to 20 percent, stating it was for research reactor fuel. This level is often considered the threshold between civilian and military use, as reaching 20 percent represents roughly 80 percent of the effort needed to produce weapons-grade material.
Under the 2015 agreement with six world powers, Iran was required to limit uranium enrichment to 3.67 percent and keep its stockpile below 660 pounds. As part of that deal, Iran shipped out about 25,000 pounds of uranium abroad. However, after efforts to revive the agreement failed, Iran increased enrichment levels to 60 percent—close to weapons-grade. Following Trump’s return to power in 2025, uranium stockpiles grew rapidly, with international nuclear monitors describing it as one of the fastest increases in history.
In June 2025, during a 12-day conflict, several Iranian nuclear facilities—including those at Natanz and Fordow—were struck, and storage tunnels in Isfahan were also bombed. A month later, Iran halted cooperation with the international nuclear watchdog, suspending inspections. As a result, the exact location of the 11-ton uranium stockpile remains unknown.
Experts believe that some of the material may be buried under debris, making recovery or identification extremely difficult. Even if recovered, turning it into a weapon could take more than a year. The Trump administration claims U.S. satellites are monitoring the movement of this uranium and that recent strikes have rendered the stockpile less usable for Tehran, though risks have prevented the deployment of special forces to retrieve it.
Rafael Grossi has reiterated that most of the highly enriched uranium is likely still at the Isfahan complex, which, although damaged, was not completely destroyed. Satellite imagery reportedly showed 18 blue container trucks entering a tunnel there before the conflict, leading to speculation that they were carrying enriched uranium. Some stock may also remain at Natanz.
U.S. and Israeli intelligence believe that part of the stockpile may have been moved to a secret facility in the Zagros Mountains, where enhanced security measures are in place. There are also suggestions that entry points have been altered to create confusion.
According to international nuclear data, Iran currently possesses around 970 pounds of uranium enriched to 60 percent, theoretically enough to produce more than 10 nuclear warheads. Experts warn that even if the stockpile’s location is identified, securing it would be extremely complex and pose major military and technical challenges.
Nuclear weapons expert David Albright has cautioned that if these materials are not seized, Iran could quickly advance toward developing nuclear weapons, even in small, hidden facilities. He compared Iran’s long-term uranium buildup to storing vast wealth in a bank. Meanwhile, Harvard University professor Matthew Bunn বলেছেন that once identified, the stockpile must be secured quickly; otherwise, future diplomatic efforts with Iran could become far more difficult.
Analysts warn that if the situation is not resolved, there is a strong possibility of renewed conflict within the next 6 to 12 months.
How did Iran stockpile 11 tons of enriched uranium, and where is that stockpile?
