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1 [1] (April 6, 2026)

handle is hein.crs/govetyg0001 and id is 1 raw text is: Congressional Research Service Informing the IegisI9tive debate since 1914 Updated April 6, 2026 Iran's Nuclear Program and UN Sanctions Reimposition UN Security Council Resolution 2231 (2015), which the council adopted on July 20, 2015, implements the Joint Comprehensive Plan of Action (JCPOA) and contains other provisions concerning Iran's nuclear program, Tehran's development of missiles, and arms transfers to and from Iran. In August 2020, the United States invoked the resolution's snapback mechanism, which requires the Security Council to reimpose UN sanctions lifted pursuant to Resolution 2231 and the JCPOA. (See CRS Report R40094, Iran 's Nuclear Program: Tehran 's Compliance with International Obligations, by Paul K. Kerr.) Although that effort failed, France, Germany, and the United Kingdom (UK) (collectively known as the E3) invoked the snapback mechanism on August 28, 2025, which resulted in the sanctions' reimposition on September 27, 2025. Resolution 2231 stipulates that the council, which has been seized of the Iranian nuclear issue since 2006, was to end its consideration of the matter on October 18, 2025. The resolution's snapback mechanism would then have ceased to be operational. The 2025 invocation of snapback reimposed previously terminated sanctions and extended them and Iran's nuclear program as a subject of Security Council consideration, indefinitely. The International Atomic Energy Agency (IAEA) withdrew inspectors from Iran in June 2025 after U.S.-Israeli airstrikes on Iranian nuclear facilities, including those associated with Tehran's enrichment program. The extent to which the June 2025 strikes impacted Iran's enrichment program is unclear. IAEA has not been able to inspect the attacked Iranian nuclear facilities. Whether subsequent U.S.-Israeli strikes, which began on February 28, have affected Iran's nuclear facilities is also unclear. Background: JCPOA The JCPOA, finalized in July 2015 by Iran and China, France, Russia, the UK, the United States, and Germany (collectively known as the P5+1), requires Iran to implement constraints on its uranium enrichment and heavy water nuclear reactor programs, as well as allow IAEA to monitor Tehran's compliance with the agreement. These programs have caused international concern because they could produce fissile material for use in nuclear weapons. Prior to the JCPOA, Iran was improving its ability to produce fissile material, despite UN and other sanctions' evident success in slowing the nuclear program. At the time, IAEA and U.S. officials observed that IAEA safeguards on Iran's declared nuclear facilities likely would have detected an Iranian attempt to use them for producing nuclear weapons. (See CRS Report RL34544, Iran 's Nuclear Program: Status, by Paul K. Kerr.) Nevertheless, Iran's continuing nuclear program concerned many governments. Pursuant to the JCPOA, Tehran received relief from sanctions imposed by the European Union, United Nations, and United States. On the agreement's January 16, 2016, Implementation Day, the Security Council terminated the provisions of seven resolutions: 1696 (2006), 1737 (2006), 1747 (2007), 1803 (2008), 1835 (2008), 1929 (2010), and 2224 (2015). Resolutions 1737 (2006), 1747 (2007), 1803 (2008), and 1929 (2010) all imposed sanctions on Iran. In May 2018, President Donald J. Trump issued a memorandum stating that the United States would no longer participate in the JCPOA and would reimpose sanctions that had been suspended pursuant to the agreement. Arguing that subsequent efforts by the remaining JCPOA participants, known as the P4+1, were inadequate to sustain the agreement's benefits for Iran, Tehran has undertaken some nuclear activities that exceed JCPOA- mandated limits. Iran's Nuclear Prograrn and Selected JCPOA Provisons Beginning in July 2019, IAEA verified that some of Iran's nuclear activities were exceeding JCPOA-mandated limits; its government has since increased the number of such activities. Tehran has also curtailed IAEA monitoring of Iran's JCPOA commitments, which supplement Tehran's obligations pursuant to its IAEA comprehensive safeguards agreement and the nuclear Nonproliferation Treaty (NPT). (See CRS Report R40094, Iran 's Nuclear Program: Tehran 's Compliance with International Obligations, by Paul K. Kerr.) The NPT, which Iran ratified in 1970, includes prohibitions on obtaining or producing nuclear weapons. Comprehensive safeguards agreements empower IAEA to detect the diversion of nuclear material from declared nuclear facilities and to detect undeclared nuclear activities and material. Iran also ceased implementing the Additional Protocol to its comprehensive safeguards agreement in February 2021. Such protocols increase IAEA's ability to investigate undeclared nuclear facilities and activities in nonnuclear- weapon states by increasing the agency's authority to inspect certain nuclear-related facilities and demand information from member states. Pursuant to its JCPOA commitments, Iran is required to implement provisionally its additional protocol. Tehran was to have sought the Iranian parliament's ratification of the protocol no later than October 2023. Iran signed such an additional protocol in late 2003 but stopped implementing it in early 2006.