The UN Security Council sanctions, which were lifted under the 2015 Joint Comprehensive Plan of Action (JCPOA), were automatically reimposed via the ‘snapback’ mechanism on 27 September. The UK, France, and Germany (E3) triggered the measure a month prior, citing Iran’s “significant non-performance” and breaches of its nuclear commitments, including an enriched uranium stockpile 48 times the agreed limit. The restored sanctions prohibit the transfer of nuclear and ballistic missile technology, halt conventional arms deals, and re-establish asset freezes. The move is expected to exacerbate Iran’s already troubled economy and complicates efforts to revive diplomacy.