The United States and Iran have given contradictory accounts about whether the sites would be inspected, but Grossi said the inspections were “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 Fukushima Daiichi nuclear power plant in Japan.
He said the agreement explicitly required IAEA supervision of nuclear activities involving Iran’s nuclear material and facilities.
"Obviously, to do that, we will have to inspect. Whether this happens the day after tomorrow or in one week or in 10 days, it's important, but not essential. This is going to happen," he said.
US President Donald Trump said on Tuesday that Iran had agreed to long-term, high-level nuclear inspections, adding that he would not allow further negotiations without such an agreement.