President Trump has vowed to prevent Iran from acquiring nuclear weapons, and central to that promise is the fate of highly enriched uranium that could be used to make at least 10 bombs.
It is known that most of the uranium is stored underground, unable to be destroyed even by America’s powerful bunker-busting bombs. A U.S. military raid to retrieve uranium would pose enormous risks, including to the material itself, which could become highly toxic if it leaks or is exposed to moisture.
The Trump administration is focusing diplomatic efforts, including persuading Iran to hand over data in exchange for incentives.
“Iran is under sanctions because it has highly enriched uranium, and Iran is under sanctions because of its nuclear activities,” U.S. Secretary of State Marco Rubio said while testifying before the Senate Foreign Relations Committee on Tuesday. “If they agree to waive those things, there will be sanctions relief associated with commitments and compliance with that agreement.”
The International Atomic Energy Agency (IAEA) said in February that Iran is stockpiling about 970 pounds of 60% enriched uranium as of June 2025. Materials are often stored in scuba tank-sized containers, allowing stockpiles to be split between multiple locations.
Without full inspection by the IAEA, it is impossible to know exactly where Iran’s nuclear material is stored. Let’s take a look at where experts believe it is and why it’s so difficult to find.
The deep complex of Isfahan
Most of Iran’s enriched uranium is likely stored underground near the Isfahan nuclear facility, according to Rafael Grossi, who heads the IAEA. It would only take a few weeks to process this material for use in a nuclear weapon.
The complex is likely buried deep beneath the mountains, beyond the reach of bunker-busting bombs, according to an analysis by the Jewish Institute for National Security of America, a Washington research institute.
When the United States briefly joined Israel in last year’s 12-day war, U.S. airstrikes severely damaged the tunnel entrance to the Isfahan site. Satellite images show efforts have been made to clear debris from some inlets. But Iran covered it again with earth as a protective measure earlier this year before the latest war began in February.
Images showed earthen barriers added to defend ground operations this year, according to research institute the Institute for Science and International Security. Other new structures visible near one entrance may be shelters for defensive military equipment, said Sarah Burkhard, a senior researcher at the institute.
Some analysts say there is also limited visual evidence that Iran may have moved enriched uranium to Isfahan. Before the June 12 war, satellite images from Airbus showed a cargo truck near one of the complex’s entrances. The load was similar to containers used to transport nuclear material. The image was first reported by Le Monde.
There are still many uncertainties. “There are many unknowns about whether the material is uranium or some other chemical involved in the metallurgical processes that Iran is seeking to protect,” said Joseph Rodgers, a nuclear expert at the Center for Strategic and International Studies.
Natanz and nearby Pickaxe Mountain
A small portion of the highly enriched uranium could be at Natanz, Iran’s largest enrichment site, according to IAEA Director General Grossi.
The United States and Israel bombed Natanz in June 2025, causing severe damage. They struck again in the most recent war, in March, which may have been aimed at burying enriched uranium at the site, said Mr. Rogers, the nuclear expert. Again, the fate of the uranium there is unknown.
About a mile from the Natanz nuclear complex is another underground site called Pickaxe Mountain, which experts say has been under construction since 2020. Satellite images show Iran continued work at the site after the June 2025 war. Recently a security wall was built around it to protect against future attacks and some entrances were fortified.
Beneath the ruins of Fordo
The Fordo underground base was virtually destroyed in June 2025 when the U.S. military launched an airstrike with 12 bunker buster bombs. Satellite images in recent weeks have shown Iran has added roadblocks to roads leading to the tunnel entrance in an effort to slow a potential attack, according to the Institute for Science and International Security.
Enriched uranium may be stored in undisclosed locations other than Isfahan, Natanz, and Fordo. Experts say that without government cooperation, recovering or disposing of Iran’s stockpile could become more difficult.
“If Iran were worried about the United States or Israel or some combination trying to come in and steal the material or remove it through military force, you would think they would want to spread it elsewhere,” said Scott Roecker, vice president of the Nuclear Materials Security Program at the Washington-based Nuclear Threat Initiative.
Iran also has more uranium than its 60% enriched reserve. According to the IAEA’s most recent assessment, our country has more than 19,930 pounds of enriched uranium, including 405 pounds enriched up to 20 percent and 13,280 pounds enriched up to 5 percent.
Converting uranium to bomb grade will take time, but Iran will maintain the ability to do so as long as it maintains operational enrichment facilities.
