Highly enriched uranium (HEU) — uranium enriched to levels usable in nuclear weapons — is central to the risk of a wider conflict between the United States and Iran. International inspectors have been unable to verify Iran’s holdings since last June, after strikes on several nuclear sites. Estimates from U.N. inspectors and outside analysts suggest Iran may possess roughly 1,000 pounds of uranium enriched to about 60 percent U-235, and possibly enough HEU overall to be further processed into material for roughly ten nuclear weapons.
President Trump has said the United States will take whatever HEU remains, either through negotiation to permit experts to secure and remove the material or by force. That latter option recalls Project Sapphire, a covert 1994 mission that removed weapons-grade uranium from Kazakhstan after the Soviet collapse and has been suggested as a blueprint for similar removals.
Project Sapphire involved Andrew Weber, then a junior U.S. foreign service officer, who helped discover a cache of uranium enriched to about 90 percent U-235 — effectively weapons-grade — at a Kazakh facility. Through quiet diplomacy and relationship-building with the plant director, U.S. officials obtained access. A combined team from the Departments of Defense and Energy flew in heavy-duty drums and other equipment, packaged more than 1,300 pounds of HEU under cover of a humanitarian mission, and transported it by aircraft to secure storage in the United States. The operation used three C-5 Galaxy cargo planes, required a compact specialized team, remained covert, and took about six weeks.
But experts say Iran presents a much harder problem. Facilities such as the Isfahan site are thought to be deep under mountains and protected in hardened tunnels; stockpiles may be stored in scuba-tank-sized containers in caverns that could be difficult or impossible to reach with conventional bombing. Satellite imagery has shown entrances to subterranean spaces blocked with earth and roadblocks, indicating preparations to deny access. Pickaxe Mountain, another suspected location, displays signs of large underground construction carved into solid rock.
Andrew Weber and others who worked on past removals warn that a unilateral U.S. insertion into Iran would be extremely risky. Matthew Bunn, a former White House nuclear advisor at Harvard’s Belfer Center, emphasizes a key point: strikes and even war can damage facilities and delay programs, but they do not erase knowledge or the ability to rebuild. You cannot simply “bomb away” expertise or entirely eliminate enriched material if it remains dispersed or deeply buried.
Operationally, removing HEU without the host’s cooperation would be enormously demanding. Scott Roecker, a former senior official at the National Nuclear Security Administration (NNSA), notes that past HEU removals depended on agreement and cooperation from host governments. The NNSA has overseen the removal of more than 16,000 pounds of HEU worldwide, but those missions were conducted with a willing partner. In contrast, Iranian officials have publicly rejected the idea of handing over HEU.
A forced seizure would likely require far more than the small, covert footprint used in Project Sapphire. U.S. Special Operations forces would need to secure facilities and hold broad perimeters, while technical teams excavated and packaged material stored in deep tunnels. That could involve thousands of troops, extensive logistics, construction of access infrastructure, heavy equipment, and sustained protection against asymmetric threats. Vice Admiral Robert Harward, a retired Navy SEAL who once served as deputy director of U.S. Central Command, cautioned that such an operation would be high-risk, probably take many weeks, and draw on all military branches. Forces would also be exposed to Iranian retaliatory capabilities — drones, missiles, and kinetic systems — and planners would have to accept the possibility of casualties.
Even with a large force, recovery could be incomplete. Deep underground storage, dispersed sites, or materials moved to hard-to-reach locations would limit the effectiveness of kinetic strikes and complicate retrieval. Specialized containment, transportation, and safeguards would be required to prevent contamination, loss, or proliferation during removal and transfer.
Because of these challenges, many experts argue the most viable route is negotiation combined with stringent verification. A negotiated agreement enabling international experts to inventory, secure, and remove HEU under robust monitoring would reduce risk and limit the need for force. Matthew Bunn and others stress that a durable solution must both eliminate highly enriched uranium from Iran’s control and institute deep, continuing verification measures. That is difficult because of longstanding distrust: Iran has repeatedly denied weaponization activities in the past before inspections exposed undisclosed programs, and recent hostilities and the breakdown of talks have only deepened skepticism.
If diplomacy fails, choices narrow to either a risky military seizure or continued efforts to contain and monitor Iran’s program remotely. A military option would require a massive, sustained commitment: secure perimeters, heavy logistics, specialized containment and transport capabilities, protection from asymmetric attacks, and a political willingness to accept potential casualties and regional consequences. Even then, success would be uncertain and potentially incomplete.
In summary, removing Iran’s HEU would be far more complicated than Project Sapphire. The Kazakh removal succeeded because of secrecy, diplomacy, and a permissive host. By contrast, Iranian consent appears unlikely, and deeply buried, hardened facilities would pose severe technical and operational obstacles. Most experts conclude that any realistic path to securing Iran’s HEU relies on negotiation and internationally verified mechanisms; without cooperation, attempts to seize or eliminate such material would be dangerous, uncertain, and likely costly in lives and regional stability, leaving the international community with a persistent proliferation challenge.