France, Germany and the UK have notified the United Nations they are prepared to reimpose UN sanctions on Iran unless Tehran returns to nuclear talks by the end of August.
In a letter sent on 12 August, the three governments – the E3 – warned they would activate the Security Council “snapback” mechanism if there is no diplomatic progress or if Iran declines an extension to keep negotiations alive.
The FT said the ministers’ message followed “serious, frank and detailed” talks with Iranian officials in Istanbul in July, described as the first face-to-face meeting since reported Israeli and US strikes on Iranian nuclear facilities. The letter stated: “If Iran is not willing to reach a diplomatic solution before the end of August 2025, or does not seize the opportunity of an extension, the E3 are prepared to trigger the snapback mechanism.”
Under UN Security Council Resolution 2231, which endorsed the 2015 nuclear agreement, any JCPOA participant state can notify the Council of “significant non-performance”. That step begins a process under which, after 30 days, prior UN sanctions automatically return unless the Council adopts a resolution to continue sanctions relief. Because any permanent member can veto such a resolution, snapback cannot be blocked once validly triggered by a participant. The E3 remain participant states and, in principle, are able to initiate the process.
Timing is a factor. Key provisions of Resolution 2231, including access to the snapback route, are due to lapse on 18 October 2025 unless action is taken beforehand. European officials have been discussing contingency options, amid concern that the window to use UN measures is closing. The letter indicates the E3 are prepared to act before that deadline if talks do not resume.
Tehran has criticised the threat. According to the FT, Iranian officials argue the European trio lack legal or moral grounds to restore UN measures and have warned that, if snapback is invoked, the E3 could be excluded from any subsequent discussions. Iran has sought security guarantees and compensation from Washington in previous exchanges about returning to a deal framework.
If invoked, snapback would reinstate the body of UN sanctions that applied before 2015, including restrictions on arms transfers, ballistic missile activity, and the designation of entities and individuals involved in nuclear and missile programmes. Member states would again be obliged to enforce these measures. The move would add to existing US and EU sanctions, and could complicate separate diplomatic tracks, including indirect contacts via intermediaries.
The Istanbul meeting referenced by the E3 was the first in-person channel for some time. Western governments say they remain open to a negotiated outcome that places verifiable limits on Iran’s nuclear activities, working alongside the International Atomic Energy Agency. The FT reported that the E3’s warning came after Iran did not respond to an offer to extend talks to avoid the need for snapback.
The warning also follows a show of coordination among European leaders. On 24–25 June, Emmanuel Macron, Friedrich Merz and Keir Starmer met on the sidelines of the NATO summit in The Hague, where they called on Iran to come to the negotiating table amid wider regional tensions. The E3’s letter sets a concrete deadline and signals a willingness to use UN instruments if diplomacy stalls.
Next steps would be procedural but significant. A formal notification to the Security Council would start the 30-day clock. Unless the Council passed a resolution to maintain relief – an outcome viewed as unlikely given veto dynamics – the pre-JCPOA sanctions regime would resume automatically. European officials indicate that snapback is designed to be rapid and legally self-executing once the threshold is met.
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