On Thursday, the United Kingdom, France and Germany — known as the E3 — formally initiated the snapback mechanism, threatening to reinstate UN sanctions on Iran in response to Tehran's nuclear deal violations and its recent decision to suspend cooperation with the International Atomic Energy Agency (IAEA).

As an appendix to the 2015 nuclear deal (JCPOA), the snapback is a provision that automatically reinstates all pre-deal UN sanctions unless the Security Council votes to maintain their suspension within 30 days. The mechanism is "veto-proof": If the necessary votes are not secured, the sanctions are reimposed automatically, with no new vote required. 

Iran has strongly condemned the move. In calls with European leaders, statements and posts on X, Foreign Minister Abbas Araghchi rejected it as "immoral, unjustified and unlawful," accusing the E3 of acting on behalf of Israel and the United States and warning of Iran's proportional response. 

Iran's top diplomat has urged the E3, however, to reconsider the process and called for resumption of talks that guarantee Iran's rights. The minister has also written to the UN Security Council, asking it to reject what he called the "deceitful politics" of the European powers.