Under JCPOA, Iran agreed to eliminate its stockpile of medium-enriched uranium, cut its stockpile of low-enriched uranium by 98%, and reduce by about two-thirds the number of its gas centrifuges for 13 years. For the next 15 years Iran will only enrich uranium up to 3.67%. Iran also agreed not to build any new heavy-water facilities for the same period of time. Uranium-enrichment activities will be limited to a single facility using first-generation centrifuges for 10 years. Other facilities will be converted to avoid proliferation risks. To monitor and verify Iran's compliance with the agreement, the International Atomic Energy Agency (IAEA) will have regular access to all Iranian nuclear facilities. The agreement provides that in return for verifiably abiding by its commitments, Iran will receive relief from U.S., European Union, and United Nations Security Council nuclear-related sanctions.
On 13 October 2017, U.S. President Donald Trump announced that the United States would not make the certification provided for under U.S. domestic law, but stopped short of terminating the deal.
IAEA inspectors spend 3,000 calendar days per year in Iran, installing tamper-proof seals and collecting surveillance camera photos, measurement data and documents for further analysis. IAEA Director Yukiya Amano stated (in March 2018) that the organization has verified that Iran is implementing its nuclear-related commitments. On 30 April 2018 the United States and Israel said that Iran had not disclosed a past covert nuclear weapons program to the IAEA, as required by the 2015 deal.
On 8 May 2018, Trump announced United States withdrawal from JCPOA. Following the U.S.'s withdrawal, the EU enacted an updated blocking statute on 7 August 2018 to nullify US sanctions on countries trading with Iran. In November 2018 U.S. sanctions came back into effect intended to force Iran to dramatically alter its policies, including its support for militant groups in the region and its development of ballistic missiles.
In May 2019, the IAEA certified that Iran was abiding by the main terms of the deal, though questions were raised about how many advanced centrifuges Iran was allowed to have, as that was only loosely defined in the deal.
On 1 July 2019, Iran announced that it had breached the limit set on its stockpile of low-enriched uranium, which the IAEA confirmed.
On 5 January 2020, in the aftermath of the Baghdad Airport Airstrike that targeted and killed Iranian general Qassem Soleimani, Iran declared that it would no longer abide by the limitations of the deal but would continue to coordinate with the IAEA, leaving open the possibility of resuming compliance.