The Joint Comprehensive Plan of Action included a substantial international oversight and verification regime, primarily carried out by the International Atomic Energy Agency.
The agreement did not create completely unrestricted “anytime, anywhere” inspections, but it did establish unusually intrusive monitoring measures, including:
Continuous monitoring of key nuclear facilities
Regular on-site inspections by IAEA inspectors
Electronic surveillance and enrichment monitors
Environmental sampling
Tracking of uranium stockpiles and centrifuges
Expanded access under Iran’s implementation of the Additional Protocol
A dispute-resolution mechanism that could compel access to suspicious undeclared sites within a set timeframe
The IAEA repeatedly stated during the main implementation period (2016–2018) that it was able to access the sites it needed and verify Iran’s compliance with nuclear-related commitments.