Explainer: Timing of Key Sunsets in Nuclear Deal

International restrictions on Iranian weapons—which include “sunset clauses” with expiration dates—were imposed by the 2015 nuclear agreement and U.N. Security Council Resolution 2231, which endorsed the deal. The clauses cover Iran’s nuclear program, missile production, arms trade, and conventional weapons. The dates range from 2020 to 2041. The Iran nuclear, known formally as the Joint Comprehensive Plan of Action (JCPOA), also requires the lifting of U.S. and European economic sanctions. Some restrictions and monitoring requirements, however, are permanent. The JCPOA, for example, stipulated that Iran can never “seek, develop or acquire” nuclear weapons.

By 2023, however, many of the sunset clauses imposed by the JCPOA and the U.N. were made obsolete because President Trump withdrew the United States from the international accord in May 2018, which led Iran to begin breaching its obligations in July 2019. Iran’s program was “galloping ahead” with “very limited visibility,” Rafael Grossi, director general of the International Atomic Energy Agency (IAEA), the U.N. nuclear watchdog, said in July 2022.

In October 2023, a set of U.N. restrictions on Iran’s missile program expired on what was supposed to be Transition Day, a milestone eight years after the adoption of the JCPOA. Under Resolution 2231, Iran had been prohibited from exporting or importing certain missiles, drones and related technologies without U.N. Security Council permission. 

But the expiry was unlikely to have a significant impact on Iran’s weapons programs in the immediate term, Valerie Lincy, the executive director of the Wisconsin Project on Nuclear Arms Control, told The Iran Primer. “Iran has long flouted these restrictions, testing, using, and/or transferring delivery vehicles (drones and missiles).” Furthermore, the expiring sanctions some 80 Iranian entities and individuals were also outdated. “Many of the sanctioned officials have moved on to new positions, and the entities listed use front or shell companies to conduct procurement,” Lincy added. “The cost is likely to be over the longer term and in the message it sends globally: a sense that the floor on restrictions against Iran has dropped just as the Iranian proliferation threat is expanding, with drone exports to Russia, ongoing missile and drone transfers to the Houthis, a burgeoning space launch program which has direct applications to long-range missile development, and military assistance to Hamas.”

The following is a timeline of key sunset clauses among the dozens of restrictions imposed as part of the nuclear deal brokered by the world’s six major powers.

 October 2020

• Expired: U.N. embargo that bans Iran from importing conventional weapons and any country from exporting most conventional weapons.
• Expired: U.N. ban on any country giving visas or permitting visits by dozens of Iranians involved in nuclear research, missile development or production, and other defense industries.

October 2023

• Expired: U.N. restrictions on Iran’s research, development and production of ballistic missiles designed to be capable of delivering nuclear weapons.
• Expired: U.N. ban on Iran’s on import and export of missile-related technology, including missiles and drones with a range of 300 kilometers (186 miles) or more.
• Iran was supposed to seek parliamentary ratification of the Additional Protocol, which grants the IAEA more intrusive access to facilities and information about Iran’s nuclear fuel cycle, from mining the uranium to enriching it and eventual disposal of it.
• The U.S. was required to seek congressional legislation that ends sanctions on key economic sectors that Washington “suspended” as part of the nuclear deal.
• The U.S. was required to remove certain individuals and entities linked to Iran’s nuclear program from its sanctioned list. It did not remove sanctions. 
• The E.U. was required to lift its remaining sanctions on Iran’s nuclear program. It kept restrictions in place. 

July 2024

• The JCPOA to lift some limits on Iran’s testing of advanced IR-6 and IR-8 centrifuges that enrich uranium.
• The JCPOA and U.N. bans due to expire on Iranian production of IR-6 and IR-8 centrifuges, although still without the rotors used to spin and enrich uranium.

January 2026

• U.N. Security Council Resolution 2231 due to expire, thus terminating its provisions, including the so-called “snapback” mechanism. The process would allow the swift reimposition of U.N. sanctions on Iran in the event of “significant non-performance of commitments under the JCPOA.”
• The U.N. Security Council due to “end consideration” of Iran’s nuclear program.
• The E.U. due to lift its remaining economic sanctions on Iran.
• The JCPOA to lift restrictions on the number of IR-1 centrifuges that Iran is allowed operate to enrich uranium.
• The JCPOA to lift restrictions on Iranian testing of advanced IR-6 and IR-8 centrifuges.
• The JCPOA to lift restrictions on Iranian production of IR-6 and IR-8 centrifuges with rotors.
• The JCPOA to end procurement channel for approving Iran’s nuclear-related imports.

January 2031

• The JCPOA to lift the 3.67 percent cap on Iranian uranium enrichment.
• The JCPOA to allow Iran to stockpile more than 300 kilograms—or 660 pounds—of enriched uranium.
• The JCPOA to lift the ban on Iranian uranium enrichment at the Fordo facility.
• The JCPOA to lift the ban on Iranian research and development on uranium and plutonium metal.
• The JCPOA to lift the ban on Iranian reprocessing of spent fuel from a nuclear reactor.
• The JCPOA to lift the limits on Iranian accumulation of heavy water.
• The JCPOA to allow Iran to construct new heavy water reactors.
• The JCPOA to lift some IAEA monitoring of Iran’s nuclear activities.

January 2036

• The JCPOA to lift IAEA monitoring of Iranian production, assembly and storage of centrifuges.

January 2041

• The JCPOA to end IAEA monitoring on Iran’s uranium mines and mills.