France, Germany and the United Kingdom have formally told the United Nations they are prepared to trigger the UN Security Council’s “snapback” mechanism and reinstate comprehensive sanctions on Iran unless Tehran resumes nuclear negotiations and restores full cooperation with the International Atomic Energy Agency by the end of August 2025. The warning was delivered in a joint letter from the three foreign ministers dated 12 Aug and first reported by the Financial Times. The so-called E3 said they remain committed to a diplomatic settlement and have offered a limited extension of provisions under Resolution 2231 to facilitate direct U.S.–Iran talks. If Iran does not engage, the ministers wrote, they will move to re-impose all UN measures lifted under the 2015 Joint Comprehensive Plan of Action, including the global arms embargo and economic restrictions. European concern has intensified since Israeli and U.S. air strikes on Iranian nuclear sites in June and Tehran’s subsequent curbs on IAEA inspections. The E3 letter cites Iran’s stockpile of uranium enriched to levels “more than 40 times” higher than the deal permits as evidence of “significant non-performance.” Iranian officials have responded that any snapback would be illegal and warned that parliament could vote to withdraw from the Nuclear Non-Proliferation Treaty. Reinstating UN sanctions would add to existing U.S. economic pressure and further isolate the Islamic Republic at a moment when its economy is already struggling.