The International Atomic Energy Agency (IAEA) said Friday its inspectors have departed Tehran and arrived safely to Vienna after Iran suspended cooperation in the wake of attacks on its nuclear program by Israel and the United States.

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.

The decision means that international inspectors will not be able to oversee sites. Experts have warned that Tehran could revive plans to build a bomb.