The snapback mechanism is a procedural innovation embedded in UN Security Council Resolution 2231 (2015), which endorsed the Joint Comprehensive Plan of Action (JCPOA) between Iran and the E3/EU+3 (France, Germany, the United Kingdom, China, Russia, and the United States). It allows any JCPOA "participant State" to notify the Council of significant non-performance by Iran, triggering a 30-day window after which the pre-JCPOA UN sanctions resolutions are automatically reinstated unless the Council adopts a resolution to continue sanctions relief.
The mechanism is designed to be veto-proof in reverse: because the default outcome is reimposition, a permanent member sympathetic to Iran cannot block snapback by vetoing. This inverts the normal P5 veto dynamic and is the feature that made the JCPOA politically saleable in Washington in 2015.
The previously terminated measures that snap back include:
- The arms embargo and ballistic-missile restrictions of earlier resolutions
- Asset freezes and travel bans on listed Iranian individuals and entities
- Restrictions on nuclear- and missile-related transfers under resolutions such as 1696 (2006), 1737 (2006), 1747 (2007), 1803 (2008), and 1929 (2010)
The United States attempted to invoke snapback in August 2020 under the first Trump administration, despite having withdrawn from the JCPOA in May 2018. Thirteen of fifteen Council members rejected the US claim to "participant" status, and the snapback was not treated as effective by the Council president or the wider UN membership.
In 2025, the E3 (France, Germany, and the UK) notified the Council of Iranian non-compliance, triggering the procedure before Resolution 2231's own sunset date of 18 October 2025, after which the snapback option would have expired. Snapback is distinct from unilateral US, EU, or UK sanctions, which operate under separate domestic and regional legal authorities.
Example
In August 2020, the United States attempted to invoke snapback against Iran at the UN Security Council; 13 of 15 members rejected Washington's standing as a JCPOA participant after its 2018 withdrawal.