Return of the trigger mechanism threatens to collapse Iran nuclear diplomacy

Western powers, led by the European JCPOA trio, prepare a snapback sanctions push as Tehran warns of NPT withdrawal and an irreversible diplomatic collapse

Vali Kaleji

The Cradle

In the past two weeks, the UK, France, and Germany have spearheaded a coordinated effort before the International Atomic Energy Agency (IAEA) Board of Governors to declare Iran non‑compliant, and set the stage for UN snapback sanctions under Articles 36–37 of the Joint Comprehensive Plan of Action (JCPOA) – also known as the Iran nuclear deal. 

In response, Iran's UN envoy Amir Saeid Iravani warned on 12 June that triggering the mechanism would compel Tehran to withdraw from the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) under Article X – declaring Europe’s move “legally baseless and politically reckless.”

The return of the 'trigger mechanism'

First introduced in the JCPOA in 2015 and endorsed by UN Security Council Resolution 2231, the “trigger mechanism” – also known as “snapback sanctions” – allows any JCPOA member state to unilaterally reimpose UN sanctions on Iran if it deems the country to be in violation of the deal. 

This provision was a major concession to Washington during the original negotiations, designed to bypass the Security Council's veto structure and ensure a swift response to any perceived Iranian breaches.

The process is straightforward: If a JCPOA signatory files a complaint to the deal's Joint Commission, the dispute is examined over 15 days. Failing resolution, it escalates to the UN Security Council. If the Council does not pass a resolution to continue lifting sanctions, they are automatically reinstated. Notably, no permanent member can veto the return of sanctions, only the extension of their suspension – a critical inversion of the usual Security Council procedure.

This mechanism, designed for automaticity, renders it largely immune to political obstruction. Should it be triggered, all Security Council sanctions lifted under the JCPOA would snap back, including the arms embargo, asset freezes, travel bans, and restrictions on Iran's nuclear and ballistic activities.

E3 alignment with Washington and Tel Aviv

Following the unilateral US withdrawal from the JCPOA in 2018 during US President Donald Trump's first presidential term, Washington's 2020 attempt to invoke the trigger mechanism failed. Most Security Council members, including Russia and China, rejected the US claim of having standing under the deal. 

The US secured support only from the Dominican Republic; Russia and China opposed the move, while the European trio and eight other members abstained. Yet four years later, the landscape has shifted sharply.

Relations between Tehran and the European JCPOA signatories – France, Germany, and the UK – have deteriorated to their lowest point since the 1979 Islamic Revolution. These rifts extend far beyond the nuclear file: European officials cite Iran's missile program, support for Axis of Resistance groups, detentions of dual nationals, and its alliance with Russia in the Ukraine war as cumulative grievances.

French Foreign Minister Jean-Noel Barrot laid down the gauntlet in an April speech to the Security Council: If European security is threatened, Paris “will not hesitate for a single second to reapply all the sanctions that were lifted 10 years ago.” Iran's UN representative dismissed the threat as a breach of international law by a country failing to uphold its own commitments.

Iran's UN representative, Iravani, countered that France's threat to activate the so-called snapback mechanism – despite its own failure to honor JCPOA obligations – violates core tenets of international law.

While Russia and China maintain that only JCPOA parties can invoke the snapback clause, their vetoes hold no sway here. The mechanism's design strips them of the ability to block sanctions reinstatement, leaving Iran exposed even to the initiative of its nominal allies.

IAEA pressure mounts as uranium stockpiles grow

Tensions were further inflamed by a 31 May report from the IAEA, which revealed that Iran's stockpile of 60 percent enriched uranium had jumped nearly 50 percent since February. At 408.6 kilograms, the material is technically just one step short of weapons-grade.

Iran slammed the IAEA report as politicized and reliant on forgeries from the Israeli occupation state. The Iranian Foreign Ministry accused the agency of using “forged documents provided by the Zionist regime [Israel]” and reiterated “previous biased and baseless accusations.”

Yet the report served as a pretext for new censure. On 12 June, the IAEA Board of Governors adopted a resolution condemning Iran’s “non-compliance” with its obligations, according to diplomatic sources cited by AFP. The motion, drafted by the US, Britain, France, and Germany, passed with 19 votes in favor out of 35. 

Abdolreza Faraji Rad, a former Iranian diplomat, sees the IAEA's accusations as a likely precursor to the activation of the trigger mechanism.

Iran's NPT withdrawal threat resurfaces

Tehran has repeatedly warned it may withdraw from the NPT if snapback sanctions are reinstated. Article X [10] of the NPT provides a “right” to withdraw from the treaty. Iran has repeatedly openly threatened to take such a decision. Deputy Foreign Minister Kazem Gharibabadi has explicitly tied Iran's NPT membership to Europe's behavior. “If Europe implements snapback, our answer is to withdraw from the NPT.”

Such a move could mark a point of no return. Withdrawal from the NPT would formally end Iran's commitment to peaceful nuclear development, open the door to weaponization, and provide Tel Aviv and Washington with a potential pretext for preemptive military strikes on Iranian facilities.

Diplomacy on the brink

While indirect negotiations between Tehran and Washington continue, a snapback vote in the UN Security Council could shatter the process entirely. It would deepen the alignment between Europe and Israel and expose rifts with Washington, should the US oppose such a move.

Despite mounting pressure, diplomacy has not yet collapsed. In recent months, Iran and the E3 have held four rounds of talks – on 29 November, 13 January, 24 February, and most recently on 16 May in Istanbul. That final meeting coincided with the resumption of US–Iran backchannel talks, signaling that some diplomatic oxygen remains.

Still, the threat of a full-blown crisis looms. The revival of the trigger mechanism could ignite an irreversible chain reaction: reimposed sanctions, NPT withdrawal, possible nuclear weaponization, and military confrontation.

Avoiding that path requires giving diplomacy one last chance before the door slams shut.