For decades, Iran has been subject to rigorous inspections of its core nuclear sites. Inspectors would visit its enrichment sites and check its stockpile of enriched uranium every couple of days, ensuring that Iran wasn’t diverting fissile material for a nuclear weapon.

U.N. nuclear inspectors on Friday departed from Iran two days after the Middle Eastern nation suspended cooperation with the program and weeks after the United States and Israel bombed nuclear sites.

The withdrawal of international inspectors comes amid heightened concerns that Iran, battered by Israeli and U.S. strikes, may be driven to try to build a nuclear bomb.