Iran has stated it will not permit nuclear inspectors back into nuclear sites that were struck by the U.S. and Israel. These sites include a majority of the crucial facilities the International Atomic Energy Agency (IAEA) requires access to for inspections.

U.S. President Donald Trump and IAEA Director-General Rafael Grossi have previously insisted that nuclear inspectors must have full access to all facilities at any time. Iran possesses over 400 kilograms of 60% enriched uranium, which is located at the Natanz, Isfahan, and Fordow nuclear facilities. Israel believes some Iranian centrifuges survived Israeli attacks.

Leaks from U.S. officials during nuclear negotiations indicated that Iran had agreed to allow its 60% enriched uranium to be removed or diluted. David Albright, President of the Institute for Science and International Security, stated, "In order to neutralize the uranium threat fully, Iran would need to dilute its uranium down to the natural level (0.7%), effectively making it a product with no economic value."

Albright explained, "The level of dilution has not been publicly agreed upon." He said, "If Iran only dilutes it down to 3.67%, as it did during the 2015 Iran nuclear deal, that it would still leave it about 70% of the way to weapons-grade uranium." Albright also noted that if Iran used 1,000 IR-6 centrifuges to return 3.67% enriched uranium to higher levels, this could be accomplished in four to five months, even if the centrifuges were not operating optimally.

Approximately 20,000 Iranian centrifuges were operational before June 2025. The U.S. destroyed the Fordow nuclear facility during Operation Midnight Hammer. The war between the U.S./Israel and Iran concluded on April 7, 2026, and various U.S. forces have withdrawn from the region since early April 2026.

Iran was constructing the Pickaxe Mountain nuclear facility deeper than previously known in 2021. This facility is not currently considered operational. As of June 4, 2026, top U.S. and Israeli sources expressed concerns regarding the viability of destroying the Pickaxe Mountain facility through aerial attacks. Additionally, the United States Central Command conducted attacks on Iranian assets located near the Strait of Hormuz.

Why It Matters

Iran's refusal to allow nuclear inspectors back into sites hit by the U.S. and Israel creates a potential obstacle for international monitoring efforts. The facilities that Iran is restricting access to are key to the International Atomic Energy Agency's inspection requirements. The presence of over 400 kilograms of 60% enriched uranium at several Iranian nuclear sites, combined with the capabilities of centrifuges that may have survived attacks, indicates ongoing concerns regarding Iran's nuclear program following the conclusion of the war between the U.S./Israel and Iran in April 2026.