The USS Spruance, a guided missile destroyer, intercepted the Iranian-flagged cargo ship Touska in the Gulf of Oman. The Touska, travelling from China to Bandar Abbas in Iran - under US Treasury sanctions for prior illegal activity - refused US Navy orders to halt over the course of six hours. CENTCOM confirmed: "American forces acted in a deliberate, professional, and proportional manner to ensure compliance." Trump announced the seizure on Truth Social: "A guided missile Destroyer, USS Spruance, intercepted the TOUSKA in the Gulf of Oman, and gave them fair warning to stop. The Iranian crew refused to listen, so our Navy ship stopped them right in their tracks by blowing a hole in the engineroom. Right now, US Marines have custody of the vessel." Iran's military issued a furious statement via IRIB: "The 'aggressor United States,' by violating the ceasefire and engaging in maritime highway robbery, attacked an Iranian commercial vessel in the waters of the Sea of Oman. The US destroyed the ship's navigational equipment and deployed troops on the deck, effectively carrying out an act of aggression." Iran's National Security Council said Iran was "determined to exercise supervision and control over traffic through the Strait of Hormuz until the war is definitively ended and lasting peace is achieved." The Touska seizure was the first boarding of an Iranian-flagged vessel since the war began - a significant escalation of the blockade from interception to physical capture. No tankers transited Hormuz on Sunday. The IRGC maintained its total anchorage ban: "No vessel should make any movement from its anchorage in the Persian Gulf and the Sea of Oman. Approaching the Strait of Hormuz will be considered cooperation with the enemy, and the offending vessel will be targeted." Trump also noted the blockade was costing Iran "$500 Million Dollars a day" while the US "loses nothing." Oil climbed sharply: Brent crude rose 7% to approximately $96.88; WTI rose 7% to approximately $90.33. US average gasoline hit $4.05/gallon nationally. Energy Secretary Chris Wright told CNN prices might not return below $3 "until next year."

Following the Touska seizure, Trump posted his most extreme threat since the war began: "We're offering a very fair and reasonable DEAL, and I hope they take it because, if they don't, the United States is going to knock out every single Power Plant, and every single Bridge, in Iran. NO MORE MR. NICE GUY!" Trump also accused Iran of committing "a total violation of our ceasefire agreement" by firing on ships in the strait. He simultaneously confirmed that US negotiators - Vice President Vance, Special Envoy Steve Witkoff and Jared Kushner - were travelling to Islamabad for a second round of talks. Iran, however, moved to cancel those talks. Iran's state agency IRNA reported Tehran was refusing to participate, citing the US's "excessive demands," "unrealistic expectations," and the continuation of the naval blockade. Iran called the blockade a breach of the ceasefire that made good-faith negotiations impossible. Trump convened another Situation Room meeting with VP Vance, Secretary Rubio and Defense Secretary Hegseth to address the Hormuz standoff. Trump departed the White House to play golf after the meeting, without issuing an immediate statement on a retaliatory posture - a signal Washington believed the talks track was not yet fully dead. Iranian sources told CNN that Iran's delegation would nonetheless arrive in Pakistan on Tuesday, contradicting IRNA - creating deliberate ambiguity about whether Round 2 would proceed.

Staff Sergeant Florian Montorio, 40, of France's 17th Parachute Engineer Regiment from Montauban, was killed in an ambush while serving as part of the UN Interim Force in Lebanon (UNIFIL). His unit was clearing explosive ordnance along a road in the village of Ghandouriyeh to reach an isolated UNIFIL post that had been cut off by fighting. Montorio was killed by direct small-arms fire - France's Armed Forces Minister Catherine Vautrin confirmed it was an ambush. Three of his comrades were wounded, two seriously. UNIFIL stated the peacekeepers "came under small-arms fire from non-state actors" and announced it had launched an investigation into what it called an act that "may amount to war crimes." Macron identified Montorio publicly on X: "Sergeant Major Florian Montorio of the 17th Parachute Engineer Regiment in Montauban was killed this morning in southern Lebanon during an attack against UNIFIL. Everything suggests that responsibility for this attack lies with Hezbollah." France demanded Lebanese authorities immediately arrest those responsible. UN Secretary-General Guterres condemned the attack: "These attacks must stop," urging all parties to respect the cessation of hostilities. Hezbollah denied any connection: "We deny any connection to us with the incident that occurred with UNIFIL forces in the Ghandouriyeh area." Lebanon's army opened an investigation. Montorio was a father of two daughters and was "at the end of his military career," due to return to civilian life within months. He was the second French soldier killed in the region since the war began - the first was Chief Warrant Officer Arnaud Frion, killed by an Iranian-designed drone in Iraq's Kurdistan region in March.

Hezbollah Deputy Secretary-General Naim Qassem delivered a statement warning against a one-sided truce: "Because we do not trust this enemy, the resistance fighters will remain in the field with their hands on the trigger, and they will respond to violations accordingly." Qassem framed the ceasefire as provisional and conditional - Hezbollah would abide by it only insofar as Israel did. In Tehran, Parliamentary Speaker Ghalibaf gave a nationally televised address claiming Iran was "victorious in the field" following the war. He asserted that the US had failed to achieve its strategic goals and that Iran had agreed to the temporary truce only because Washington had accepted Tehran's demands. Ghalibaf's rhetoric was designed for domestic consumption - he simultaneously described Hormuz as under Iranian sovereign control indefinitely. However, his own diplomatic assessment told a different story: "We are still far from the final discussion. We made progress in the negotiations, but there are many gaps and some fundamental points remain." He called the US blockade an "ill-considered and ignorant decision" and stated: "It is impossible for others to pass through the Strait of Hormuz while we cannot." Iran's state-run Foundation of Martyrs and Veterans Affairs formally announced via ISNA that the war had killed 3,468 people within the Islamic Republic - the official updated toll from Iranian authorities, though widely understood to undercount military casualties.

The Israeli military announced the establishment of a "Yellow Line" demarcation in southern Lebanon - a formal boundary structurally similar to Gaza's tactical dividing lines - designed to separate IDF forces from Hezbollah-held areas while maintaining Israel's operational freedom within its declared security buffer zone. The IDF reported eliminating a "terrorist cell" operating near Israeli troops along the newly established boundary. IDF forces also carried out demolitions in Lebanese border towns, with Lebanon's state-run NNA reporting: "The Israeli enemy is repeating its house detonating operations in the town of Bint Jbeil" and surrounding settlements. Two Israeli soldiers were killed in southern Lebanon during the ceasefire period. Command Sergeant Barak Kalfon, 48, died from wounds sustained in an incident involving an explosive device on Friday April 18. Staff Sgt. Lidor Porat was also killed in battle in southern Lebanon, with eight others wounded. The deaths highlighted that despite the 10-day truce, both sides were experiencing casualties - consistent with Israel's stated position that the Lebanon ceasefire permitted continued defensive operations. Lebanon's military separately announced it had "fully reopened" the Nabatieh-Khardali road and "partially reopened" the Burj Rahal-Tyre bridge - infrastructure destroyed during Israeli strikes - as civilian access to the south slowly resumed.