Iran's 409 Kilograms of Highly Enriched Uranium Missing Amidst Ceasefire

Despite the announcement by the U.S. President that Israel and Iran have agreed to a ceasefire, halting the exchange of missiles for the time being, the biggest mystery surrounding the conflict remains unsolved: the whereabouts of the highly enriched uranium in Tehran remains unknown.

The International Atomic Energy Agency (IAEA) acknowledged just five days after the conflict erupted that its inspectors had lost track of 409 kilograms (902 pounds) of highly enriched uranium in Iran. If Iran's Supreme Leader decides to advance towards weaponization, this amount is sufficient to produce 10 nuclear warheads.

According to estimates from U.S. regulatory authorities, this stockpile could be stored in 16 cylindrical containers, each 36 inches (91.4 centimeters) high, roughly the size of a large scuba diving tank. Each cylinder weighs approximately 25 kilograms, light enough to be carried by hand or loaded onto a small vehicle and transported to a secret location.

Even if Israel and the U.S. have effectively destroyed Iran's uranium enrichment infrastructure in the foreseeable future—though evidence is far from clear—the risk lies in the possibility that uranium close to weapons-grade could be hidden indefinitely.

The Director General of the IAEA expressed optimism that a lasting ceasefire agreement could pave the way for the resumption of Iran nuclear talks and the return of inspectors. "Hostilities must cease to ensure the necessary safety and security conditions for Iran to allow the IAEA team to enter relevant facilities and assess the situation," the Director General said at an emergency meeting of the United Nations nuclear watchdog on Monday.

The disappearance of Iran's nuclear fuel highlights the high risk taken by Israel in launching a military operation against Iran just two weeks ago. This decision was made after five rounds of talks between the U.S. and Iran failed to reach an agreement.

Prior to the attack, IAEA inspectors had meticulously tracked Iran's declared uranium stockpiles, checking multiple locations daily to ensure the materials were handled properly and not diverted for weapons production.

However, the Israeli airstrike on June 13 prompted Iran to move the relevant materials to an undeclared facility, even before the U.S. joined the operation over the weekend with more advanced bombing technology. Although the Director General has requested that Iran inform its inspectors of the new location, there is no guarantee that inspectors will be granted access, regardless of whether the ceasefire agreement holds.

Iran's parliament's National Security and Foreign Policy Commission approved a bill framework this week that requires the government to suspend cooperation with the IAEA. This means all contact with the IAEA will be suspended until "the security of the country's nuclear facilities is ensured," according to the Iranian news agency.

Iranian leaders criticized the IAEA for failing to uphold their rights under the Nuclear Non-Proliferation Treaty, a core international agreement reached half a century ago aimed at preventing the spread of nuclear weapons. The treaty allows signatory countries like Iran to acquire nuclear technology without seeking to manufacture nuclear weapons.

Since these technologies are mostly dual-use, applicable to both civilian and military domains, the treaty grants the IAEA the authority to ensure that nuclear materials are used appropriately.

Iran's representative to the IAEA stated on Monday that the decision by Israel and the U.S. to bomb Iran's nuclear facilities instead of continuing to seek a diplomatic solution has dealt an "irreversible blow" to the integrity of the treaty, rendering it a mere formality.

Even if the legal and political relationship between Iran and IAEA inspectors has not deteriorated due to military action—though it has in reality—the attacks on nuclear facilities have made inspection work more difficult. Over the past 12 days, Israeli and U.S. bombers have conducted intense strikes on the Fordow, Isfahan, and Natanz nuclear facilities, which are now littered with localized chemical and radioactive contamination, potentially causing critical inspection equipment to fail.

The whereabouts of the highly enriched uranium remain unknown.