The United States is escalating diplomatic efforts to pressure Iran over its refusal to allow nuclear inspectors access to verify its stockpile of near-weapons-grade uranium. Washington is expected to introduce a resolution calling for Iran to be referred to the United Nations Security Council, citing Tehran’s prolonged non-compliance with International Atomic Energy Agency (IAEA) inspections.
The move is set to take place during the IAEA Board of Governors’ meeting in Vienna, which began on Monday. Inspectors have been barred from reviewing Iran’s uranium inventory for the past 15 months, a restriction that coincides with a series of Israeli air strikes against Iranian nuclear sites starting in June 2025. The United States’ proposed resolution demands that Iran urgently remedy its non-compliance and allow immediate access to verify that nuclear material is not being diverted for weapons purposes.
IAEA Director-General Rafael Mariano Grossi expressed increasing frustration over Iran’s lack of cooperation, noting that Tehran has refused engagement or provision of information until broader political negotiations advance. “There’s no engagement, there is no information, and we are being told that they are not going to cooperate until there is some agreement in the wider political negotiation,” Grossi said during a press briefing.
The last time the United States referred Iran’s nuclear activities to the Security Council, Israel launched military strikes on Iranian nuclear facilities within 24 hours, leading to a 12-day conflict. The current round of hostilities began on February 28, just one day after the IAEA reported renewed activity near previously targeted sites. President Donald Trump has stated that the ongoing campaign aims to prevent Iran from developing nuclear weapons and has indicated that additional strikes against deeply buried sites may occur soon. Trump specifically mentioned targeting “Pickaxe,” a fortified facility near Natanz.
Iran dismissed calls to resume inspections as “meaningless” amid continued military attacks. Its permanent mission to the United Nations accused the United States and Israel of aggression and called on the IAEA to demand an end to such attacks against peaceful nuclear facilities protected under international agreements. Tehran maintains it has the right to safeguard its national interests.
The IAEA is currently unable to verify activities at several key facilities, including the site in the Zagros Mountains, approximately 220 kilometers south of Tehran, as well as damaged plants in Fordow, Isfahan, and Natanz. The agency reported that about 441 kilograms of lower enriched uranium and 8,600 kilograms of slightly enriched material were last accounted for at these locations. Grossi emphasized the proliferation risks posed by the agency’s limited access and urged Iran to reestablish safety verification measures as a matter of priority.
While a Security Council referral could lead to renewed sanctions or even authorization of military action, the prospects for such measures are uncertain. China and Russia have consistently opposed further punitive actions against Iran and questioned the legality of the UN sanctions reinstated last year. The IAEA Board of Governors’ session this week will be the first to feature the new U.S. ambassador, Preston Wells Griffith III, who previously served as a White House special assistant during Trump’s first term.