As the 10-day Israel-Lebanon ceasefire took effect overnight, Iranian Foreign Minister Abbas Araghchi posted on X at 8:45am local time: "In line with the ceasefire in Lebanon, the passage for all commercial vessels through Strait of Hormuz is declared completely open for the remaining period of ceasefire, on the coordinated route as already announced by Ports and Maritime Organisation of the Islamic Rep. of Iran." The announcement triggered the largest single-day move in energy markets since the war began. WTI crude tumbled 10-13% to approximately $79-81 per barrel; Brent crude dropped 10-13% to approximately $86-88 per barrel - paring roughly 30% off recent peak prices. Wall Street erupted: the Dow Jones Industrial Average gained over 1,000 points (2%+); the S&P 500 jumped 1.2-1.4% to a fresh all-time high; the Nasdaq rose 1.5%, also a record - the third consecutive week of gains, the longest streak since Halloween 2025. Stock markets in Europe also surged. Araghchi specified the opening was conditional and tied to the Lebanon ceasefire duration - and Iran would still control which vessels used designated routes. Trump confirmed the opening on Truth Social in all-capitals within minutes: "IRAN HAS JUST ANNOUNCED THAT THE STRAIT OF IRAN IS FULLY OPEN AND READY FOR FULL PASSAGE." He immediately added: "THE STRAIT OF HORMUZ IS COMPLETELY OPEN AND READY FOR BUSINESS AND FULL PASSAGE, BUT THE NAVAL BLOCKADE WILL REMAIN IN FULL FORCE AND EFFECT AS IT PERTAINS TO IRAN, ONLY, UNTIL SUCH TIME AS OUR TRANSACTION WITH IRAN IS 100% COMPLETE." He also said the blockade would end as soon as a deal was reached and that Iran was removing sea mines with American help. S&P 500 had already recovered all its war-related losses and hit an all-time high on April 15; today's opening added to those gains. Energy, shipping and airline stocks moved sharply - United Airlines and Norwegian Cruise Line among notable gainers.

Hours after the midnight ceasefire took effect, tens of thousands of displaced Lebanese civilians rushed back toward southern Lebanon and Beirut's southern Dahiyeh suburbs in massive convoys, defying warnings from both the Lebanese Armed Forces and Hezbollah about unexploded ordnance and the fragility of the truce. Highways gridlocked as families carried belongings and searched through the rubble of destroyed homes. Celebrations erupted in the streets, with crowds waving Hezbollah flags atop the ruins of flattened infrastructure - scenes that conveyed both the human scale of the war's devastation and the genuine popular relief at its pause. The Lebanese Health Ministry confirmed at least one person was killed in an Israeli strike carried out after the ceasefire began, highlighting the fragility of the pause. The civilian return created a complex security situation: Lebanese Armed Forces, UN peacekeepers (UNIFIL), and Hezbollah all cautioned against premature movement into areas with suspected mine fields and booby-trapped collapsed buildings. Over 1 million people had been displaced in Lebanon since March 2. Netanyahu stated Israel would maintain a 10-kilometre security zone inside Lebanese territory throughout the ceasefire period and that Israeli troops would not withdraw - a condition Lebanon had not accepted and which Hezbollah described as a continued occupation.

Despite Iran reopening the strait, the US naval blockade on all Iranian ports remained in full effect - CENTCOM confirmed it continued to apply to all vessels entering or departing Iranian coastal areas regardless of flag. Iranian Navy Commander Shahram Irani denounced the blockade as "piracy and maritime theft," while Iran's parliament speaker Mohammad Bagher Ghalibaf posted on X a direct threat: "If the blockade continues, the Strait of Hormuz will not remain open. Transit in the Strait of Hormuz will take place based on a 'designated route' and with 'authorization from Iran.'" Ghalibaf added that Trump "made 7 claims in one hour, all 7 of which are false," accusing the US president of using social media to wage information warfare: "Media warfare and engineering public opinion are an important part of war, and the Iranian nation is not affected by these tricks." The paradox of Day 50 was thus complete - Hormuz was technically open to commercial vessels, but Iranian oil exports remained fully blocked by the US naval cordon. The strait's opening benefited global shipping and energy consumers but gave Iran no economic relief whatsoever. Meanwhile, the USS Gerald R. Ford carrier battle group - previously in the Eastern Mediterranean - completed a transit of the Suez Canal and repositioned to the Red Sea alongside two destroyers, part of a broader US military effort to maintain a "ready stance to resume combat operations against Iran should the ceasefire not hold," per a US official. This deployment positioned the Ford to strike Iranian targets from the south if the April 22 deadline arrived without a deal.

French President Macron and UK Prime Minister Starmer co-chaired the Strait of Hormuz Maritime Freedom of Navigation Initiative summit at the Élysée Palace - the largest multilateral gathering of the war's diplomatic phase. Fifty-one countries and international organizations attended: Germany's Chancellor Friedrich Merz and Italy's PM Giorgia Meloni attended in person alongside Macron and Starmer; Australia, Canada, South Korea, Ukraine, China and India joined by video. The United States was not part of the initiative. The summit produced a joint statement from Macron and Starmer calling for "unconditional, unrestricted, and immediate reopening of the Strait of Hormuz" and committing to coordinate diplomatic, economic and military capabilities. Macron: "We all demand the full, immediate and unconditional reopening of the Strait of Hormuz by all parties," and confirmed the planned mission would be "a neutral mission, entirely separate from the belligerents to escort and secure the merchant ships transiting the Gulf." Starmer called for Hormuz to be "both lasting and a workable proposal," saying the UK and France would deploy a "strictly peaceful and defensive" joint mission to reassure shipping and support mine clearance - with "more than a dozen" countries already offering to contribute. Military planners were confirmed to meet in London the following week to operationalise the initiative. The summit coincided in real time with Iran's Hormuz announcement, producing an immediate complication: the opening was conditional and tied to a temporary ceasefire, not a permanent settlement. Both leaders welcomed the opening while emphasising it "must endure" and that work on the permanent mission would accelerate regardless.

The day's sharpest diplomatic fracture opened over nuclear claims. Trump, speaking to reporters and later at an event in Phoenix, made three specific assertions about what Iran had agreed to: first, that Tehran had agreed "very powerfully" never to have a nuclear weapon; second, that Iran would hand over its "nuclear dust" - the approximately 440 kilograms of highly enriched uranium entombed underground in Fordo, Natanz and Isfahan following the 2025 B-2 strikes; and third, that Iran had agreed to stop backing terrorist proxies including Hezbollah and Hamas. Trump also claimed peace talks would happen "in a day or two" and said he didn't see "significant differences" with Iran. Iran's Foreign Ministry spokesman Esmaeil Baghaei rejected all three assertions on state broadcaster IRIB: "Transfer of Iran's enriched uranium to the US has never been raised in negotiations. Iran's enriched uranium is sacred to us like the soil of Iran." He added: "There is no ambiguity regarding any part of the negotiations; we have clearly stated our positions." A senior Iranian official told CNN that Trump's three claims were "alternative facts." The official rejected the HEU transfer demand as a "non-starter," said Iran "will never accept" being an "exception from international law" on enrichment, and warned that Trump's "public boasting could derail the ongoing negotiations process" - raising the possibility that Iran might conclude the US was "using diplomacy to exhaust diplomacy and planning a new aggression." This divergence between Trump's public characterisation and Iran's stated positions represented the most acute pre-talks credibility gap of the entire diplomatic process. Islamabad Round 2 was expected imminently, with both sides having signalled openness - but the gap between Trump's claimed agreements and Iran's denials created a combustible starting point.