Iran's Nuclear Program: Tehran's Compliance with International Obligations [Updated March 12, 2020] [open pdf - 1MB]
From the Summary: "Several U.N. Security Council resolutions adopted between 2006 and 2010 required Iran to cooperate fully with the International Atomic Energy Agency's (IAEA's) investigation of its nuclear activities, suspend its uranium enrichment program, suspend its construction of a heavy-water reactor and related projects, and ratify the Additional Protocol to its IAEA safeguards agreement. Iran did not comply with most of the resolutions' provisions. However, Tehran has implemented various restrictions on, and provided the IAEA with additional information about, its nuclear program pursuant to the July 2015 Joint Comprehensive Plan of Action (JCPOA), which Tehran concluded with China, France, Germany, Russia, the United Kingdom, and the United States. On the JCPOA's Implementation Day, which took place on January 16, 2016, all of the previous resolutions' requirements were terminated. The nuclear Nonproliferation Treaty (NPT) and U.N. Security Council Resolution 2231, which the Council adopted on July 20, 2015, compose the current legal framework governing Iran's nuclear program."
CRS Report for Congress, R40094
Congressional Research Service: https://crsreports.congress.gov/