France, Germany and the United Kingdom have warned the United Nations that they are prepared to trigger the JCPOA “snapback” mechanism—re-imposing all pre-2015 UN sanctions on Iran—unless Tehran resumes stalled nuclear negotiations and restores full cooperation with international inspectors. In a joint letter dated 12 August and reported by the Financial Times, the three foreign ministers said Iran must commit to a diplomatic solution before the end of August 2025. They indicated the sanctions move could be postponed until mid-September if talks with the United States restart and the International Atomic Energy Agency gains access to Iranian sites. The E3 ministers argue that Iran’s enriched-uranium stockpile now exceeds the 2015 deal’s limits by more than forty-fold, and note that Tehran curtailed IAEA oversight after Israeli and U.S. strikes on its nuclear facilities earlier this summer. Iran has previously threatened to withdraw from the Nuclear Non-Proliferation Treaty should new penalties be imposed. Neither the three European capitals nor Tehran immediately commented on the letter’s publication. The warning underscores growing European concern that the landmark nuclear accord cannot be salvaged without swift action, seven years after the United States unilaterally re-imposed its own sanctions and three months before the UN embargoes are due to lapse.