Trump Sends New Nuclear Proposal to Iran with Deadline Warning; Tehran Holds Parallel EU3 Talks in Istanbul — First Since April Ceasefire — as Hormuz Blockade Enters Third Month

On May 16, 2026, President Trump sent Iran a new nuclear proposal and warned of 'serious consequences' if swift progress was not achieved — the latest escalation-diplomacy move as the Strait of Hormuz blockade entered its third consecutive month, with approximately 750 vessels trapped and $6 billion per month in Iranian oil export revenue blocked. Simultaneously, Iran held nuclear talks with the three European powers (EU3: UK, France, Germany) in Istanbul on May 16 — the first such formal dialogue between Tehran and European states since the April ceasefire ended the US-Iran military confrontation. The EU3 track is seen by Tehran as a parallel path to preserve diplomatic engagement while the US-Iran MOU track remains gridlocked. The core sticking point on enrichment duration persists: the U.S. demands a 20-year moratorium on high-level uranium enrichment; Iran has offered 5 years; sources briefed on the negotiations cite 12 years as a possible middle-ground. The May 14 congressional letter — signed by 52 senators and 177 representatives — opposing any Iran deal that permits enrichment has constrained Trump's room to maneuver and cast doubt on whether even a 12-year compromise is politically viable in Washington. Iran's parliament speakers (Ghalibaf, Rezaei) have maintained the threat of weapons-grade enrichment to 90% if Iran is attacked again; Iran holds 400–460 kg at 60% enrichment upgradeable within weeks. Iran accuses the US of 'unreasonable' and 'one-sided' demands. The EU3 Istanbul round represents a potential hedge: if the US-Iran direct track remains blocked, a European-brokered interim arrangement could provide Tehran some sanctions relief while extending the diplomatic window.