Iran faces mounting IAEA scrutiny over uninspected Isfahan nuclear site

The United Nations nuclear watchdog has expressed growing worry over an undeclared-status uranium enrichment facility in central Iran, warning that the lack of access poses significant proliferation risks, according to a confidential report seen by Reuters.

The International Atomic Energy Agency stated in the document distributed to member states that it remains "increasingly concerned" regarding the Isfahan Fuel Enrichment Plant. Iranian authorities officially declared the existence of the site to the agency in June 2025, but international inspectors have continuously been blocked from visiting the facility or examining its engineering designs.

Inspectors were originally scheduled to examine the Isfahan facility on June 13, 2025. That visit was derailed when Israel and the United States launched a 12-day joint air offensive against Iranian nuclear infrastructure, striking major enrichment installations that formed the core of the country's nuclear program.

Targets during that military campaign included an underground tunnel network in Isfahan. Diplomats suspect the enrichment plant is situated within this subterranean complex, although its precise location and condition are unverified. Because of the strikes and subsequent access restrictions, the agency noted that it cannot confirm where the facility is situated, its current operational status, or whether nuclear substances are presently stored inside.

Access across all impacted facilities remains entirely frozen. Iran has prohibited agency personnel from re-entering any of the sites hit during the June 2025 bombardment, preventing the agency from verifying inventories of enriched uranium.

IAEA Director General Rafael Grossi previously noted in March that the agency suspected a substantial quantity of Iran's most heavily refined uranium was positioned within the Isfahan tunnels. Some of Iran's amassed stockpile includes uranium enriched to levels near weapons grade.

The confidential assessment stressed that Iran must promptly update the watchdog on the conditions of its enrichment centers and account for all enriched material. The agency warned that missing verification data and the inability to inspect damaged installations represent an urgent proliferation issue that Tehran must resolve immediately.