TOKYO (AP) — The head of the U.N.’s nuclear agency signaled Wednesday that Iranian nuclear enrichment sites would be visited by his inspectors, a key component in the interim deal between the United States and Iran to reach an end to the war.

The comment by International Atomic Energy Agency head Rafael Mariano Grossi was the firmest yet from the United Nations agency, which is viewed as key in determining the status of Iran’s nuclear stockpile.

Since Israel launched a 12-day war on Iran in 2025, the IAEA has been blocked by Tehran from visiting enrichment sites where the Islamic Republic is believed to store enough highly enriched uranium to potentially build as many as 10 nuclear weapons, should it choose to rush for the bomb. Iran long has maintained that its program is peaceful, though it is the only country in the world to have uranium enriched up to 60% purity without a weapons program.

The U.S. and Iran offered contradictory remarks Tuesday about whether those sites would be inspected.

Grossi’s remarks came as U.S. Secretary of State Marco Rubio arrived in the Persian Gulf for a three-nation tour, beginning with a closed-door meeting and private working lunch in Abu Dhabi with Emirati President Mohamed bin Zayed Al Nahyan, the State Department said Wednesday.

Rubio is scheduled to travel next to Kuwait and then Bahrain for meetings with their leaders later Wednesday and Thursday.

Grossi says inspections are ‘going to happen’

“I can understand political statements, they are part of the reality, but the fundamental thing I would like to remind you and draw your attention to is that there has been a Memorandum of Understanding, signed by both presidents,” Grossi told journalists at a news conference at the tsunami-hit Fukushima Daiichi nuclear power plant.

The accord “says explicitly that the nuclear activities that are going to be carried out with the regards to the nuclear material facilities will be supervised by the IAEA — in all letters,” he said.