Aside from the question of Iranian consent, the logistical requirements for increased monitoring of Iranian sites would be daunting. It would involve more cameras, on-site inspections, satellite surveillance and other methods and might require the IAEA to assign more people and resources to its Iran team.

David Albright, president of the Institute for Science and International Security, said it was crucial to come up with a mechanism for “anytime, anywhere” inspections that go beyond the IAEA’s own special arrangements for short-notice inspections, known as the Additional Protocol.

The Additional Protocol was created in the 1990s, after the discovery of Iraq’s secret nuclear weapons program and revelations that North Korea and Romania had separated plutonium, as a means of smoking out covert arms-related activities.

“It’s extremely difficult for Iran,” said Albright, himself a former U.N. weapons inspector. “They don’t want it. They want to keep smuggling (nuclear-related dual-use items). They’re buying a lot of things, and they’re not going to want to stop.”