During a Senate Foreign Relations Committee review of the FY26 State Department budget request on May 20, U.S. Secretary of State Marco Rubio said, “There’s a separate set of sanctions out there, which are the snapback provisions that the E3 in Europe have…They are moving forward on their process, independent from ours.” With the snapback mechanism’s sunset of October 18, 2025 quickly approaching, it becomes increasingly urgent to understand what the re-implementation of these sanctions entails and how the process works.

“Snapback” Defined

The “snapback mechanism” refers to the expedited process of reimposing previously lifted UN sanctions on the Islamic Republic in Iran in accordance with UNSCR 2231, the UN Security Council resolution which endorsed the 2015 Joint Comprehensive Plan of Action (JCPOA).
- The sanctions reimposed under a successful usage of the snapback mechanism would encompass all restrictions set out in UNSCRs 1696 (2006), 1737 (2006), 1747 (2007), 1803 (2008), 1835 (2008), and 1929 (2010). This includes:

1. 1. 1. An indefinite ban on the transfer of conventional arms to and from the regime in Iran.
    2. An indefinite ban on international support for the regime's missile program.
    3. A ban on all testing and development of nuclear-capable missiles by the regime in Iran.
    4. A demand for the regime in Iran to halt all enrichment-related activities.
    5. An indefinite travel and asset ban for sanctioned individuals.

How is the Snapback Mechanism Activated?

The process of invoking the snapback mechanism begins when any current JCPOA participant—France, the UK, Germany, China, and Russia—puts forth a complaint of a “significant non-performance of commitments under the JCPOA.” Following this submission of a complaint by a JCPOA participant, the president of the UN Security Council must submit a resolution for a vote to ignore the complaint and continue sanctions relief within ten days if no other Security Council member has done so. If a resolution to ignore the complaint and continue sanctions relief is not adopted by the Security Council within 30 days following the initial submission of the complaint, then all UN sanctions detailed above “snapback” into place.
- The primary advantage to this process—when compared to the adoption of a separate, new UNSCR—is that the reimposition of sanctions cannot be vetoed by any permanent member of the Security Council. Due to the design of the JCPOA, any veto—particularly from China or Russia—of a resolution submitted to continue sanctions relief, would only result in sanctions being reimplemented when the 30-day window is over.

The snapback mechanism will no longer be available under UNSCR 2231 following October 18, 2025.

Attempt to Invoke Snapback in 2020

The United States attempted to invoke the snapback mechanism in August 2020, following its withdrawal from the JCPOA in May 2018 under the first Trump administration. Then-Secretary of State Mike Pompeo notified the UN Security Council that the U.S. believed the regime in Iran was in significant non-performance of its JCPOA commitments, triggering what it claimed was the snapback process.
- The E3’s stance was pivotal. The British, French, and German governments issued statements arguing that the U.S. “was no longer a participant and therefore lacked standing to invoke the snapback mechanism under UNSCR 2231.” They instead opted for an EU-led diplomatic approach, hoping to keep the JCPOA alive. Facing this opposition, the snapback attempt went nowhere and no other nation enforced the U.S.-declared sanctions reactivation. The Biden administration in early 2021 formally rescinded the U.S. snapback claim.

The 2020 episode underscored that snapback must be invoked by a JCPOA participant accepted as such by the Security Council, which today effectively means the E3.

Islamic Republic Reactions to Threats of Snapback

Regime officials have made it clear that a re-imposition of UN sanctions would provoke a harsh reaction from Tehran. Most alarmingly, the Islamic Republic’s leaders have explicitly warned they might quit the Nuclear Non-Proliferation Treaty (NPT) if UN sanctions are snapped back.
- In late 2024, a senior regime diplomat stated in an interview that “if the snapback mechanism is triggered, Iran will withdraw from the NPT,” and that this message had been conveyed to European officials in writing.

Tehran also indicates that snapback would end any hope of reviving the JCPOA and severely damage the regime’s relations with Europe. This month, Islamic Republic Foreign Minister Abbas Araghchi “officially warned all JCPOA signatories” against invoking snapback, saying it will have “consequences, not only the end of Europe’s role in the agreement, but also an escalation of tensions that could become irreversible.”

Current Momentum Behind Snapback

As of mid-2025, the diplomatic momentum toward snapback is building. Washington-Tehran negotiations to replace the JCPOA have continued, but multiple rounds of talks have failed to produce a breakthrough and entrenched disagreements over enrichment capabilities threaten to bring the talks to a halt. The regime in Iran remains in breach of core nuclear limits while also refusing full cooperation with international inspectors. Meanwhile, Western concerns have been heightened by the regime’s regional conduct, such as its transfer of armed drones to Russia for use in Ukraine and missiles to militant allies in the Middle East—issues that were not as prevalent in 2020. These factors have prompted a shift in European thinking. Whereas the E3 once hesitated to confront the regime for fear of derailing diplomacy, they are now openly considering snapback if Tehran does not return to compliance.
- U.S. Secretary of State Marco Rubio’s testimony in May 2025 captured this shift. Rubio noted that aside from U.S. efforts, “there’s a separate set of sanctions out there, which are the snapback provisions that the E3 in Europe have… They are moving forward on their process, independent from ours.” In other words, Britain, France, and Germany are preparing to trigger UN sanctions on their own timeline, likely well before the October deadline, regardless of U.S. domestic deliberations. Indeed, reporting indicates the E3 have warned Tehran that if no substantial progress is made in talks, they “may trigger snapback sanctions on Iran by August 2025,” essentially giving an end-of-summer ultimatum.

Any attempt to reimpose UN sanctions following October 18, 2025 would require passing a new Security Council resolution, which would likely be vetoed by Russia or China. Western officials are keenly aware that failing to act by October means losing the snapback tool permanently and allowing key sanctions to expire.