The guns fell silent across the Persian Gulf at midnight Greenwich Mean Time on Wednesday, as the ceasefire ending six weeks of open warfare between Iran and an Israeli-American coalition took effect on schedule, with the first 24 hours holding despite a final exchange of strikes in the closing hours before the deadline.

By dawn local time, a forward team of 38 United Nations military observers had landed at Muscat International Airport en route to monitoring posts along the Strait of Hormuz, the choke point that has carried roughly a fifth of the world’s seaborne oil and whose closure during the war drove crude prices to a four-year high. A second contingent flew into Doha overnight, with full deployment of the 240-person mission expected by Sunday.

“The cessation of hostilities is in effect and, as of this hour, is being respected by all parties,” U.N. Secretary-General Carla Mendes told reporters in New York early Wednesday. “We do not underestimate how fragile the next days will be. Observers will report what they see, without fear or favor.”

The ceasefire was announced Sunday in Islamabad after ten days of intensified talks mediated by Pakistan, Saudi Arabia and Egypt, with Oman serving as a back-channel conduit to Tehran. The joint communique committed Iran, Israel and the United States to halt all kinetic operations, freeze new force deployments in the theater, and submit to a U.N.-led verification regime focused initially on the Hormuz corridor and the airspace over western Iraq.

President Donald Trump, speaking briefly from the South Lawn before boarding Marine One on Tuesday evening, called the truce “a great day for the world, a great day for America, and frankly long overdue.” The president said additional details on prisoner exchanges and the eventual repatriation of remains of fallen service members would be released “very soon.” A senior White House official, speaking on condition of anonymity to discuss diplomatic timing, said the administration expected the first prisoner handover to take place in Doha within 72 hours.

In Tehran, Foreign Minister Abbas Araghchi addressed reporters at the Saadabad complex shortly after the deadline passed, framing the agreement as a defense of Iranian sovereignty rather than a concession. “The Islamic Republic agreed to this cessation because it serves the interests of our people and of regional peace,” Araghchi said. “We will judge this agreement not by its words but by whether Zionist aggression ends in fact.”

Israeli Prime Minister Benjamin Netanyahu, in a recorded statement released by his office at 3 a.m. local time, said Israel had “achieved the principal objectives of this campaign” and would maintain “complete freedom of action against any future threat.” Israeli officials confirmed that a final round of strikes against an Iranian nuclear-research facility near Arak had been carried out roughly four hours before the deadline; Iranian state media reported a final volley of ballistic missiles toward Israeli airspace shortly before midnight, the bulk of which were intercepted by Arrow and Iron Dome batteries with assistance from U.S. Navy destroyers in the Eastern Mediterranean.

The war, which began in early March with a coordinated Israeli air campaign against Iranian nuclear and industrial sites and quickly drew in U.S. naval forces after Houthi attacks on shipping, has killed an estimated 11,000 people across Iran, Iraq, Yemen, Israel and the Gulf, according to a preliminary tally published Tuesday by the International Crisis Group. U.S. military casualties stand at roughly 350 killed, the highest single-conflict toll for American forces since the second Gulf War.

Markets opened cautiously on the news. Brent crude, which had spiked above $125 a barrel last month before easing on the OPEC+ production hike announced April 1, traded down nearly $4 in early Asian hours to settle near $104. The S&P 500 futures index pointed to a stronger open in New York, while the dollar weakened modestly against a basket of currencies as safe-haven flows reversed.

“This is the first leg of what will be a long recovery for the energy complex,” said John Reilly, a commodities strategist at Citi in London. “Hormuz reopening to normal traffic, even on a phased basis, removes the single largest tail risk we have been pricing for six weeks. The question now is how quickly insurance markets and tanker operators are willing to follow the observers in.”

Insurance underwriters at Lloyd’s of London announced Wednesday morning that war-risk premiums for Gulf transits would be cut by half pending the first 14 days of observer reporting, a move that could restore meaningful volumes of Iranian and Iraqi crude to global markets within weeks if the cessation holds.

Aboard the USS Gerald R. Ford, operating in the northern Arabian Sea, Rear Adm. Christopher Vasquez, the carrier strike group commander, told a small pool of embedded reporters that U.S. forces remained on alert posture but had been ordered to break off all offensive operations at midnight GMT precisely. “Every aircraft that needed to be on deck was on deck. Every ordnance load was returned to magazine,” Vasquez said. “Now we watch, and we wait.”

Diplomats and analysts cautioned that the most dangerous period lay immediately ahead. Layla Hassan, a Beirut-based regional analyst with the Carnegie Middle East Center, noted that previous Gulf-region ceasefires have often unraveled within their first week, particularly when nonstate actors aligned with one party continued operations.

“The Houthis have not signed this paper. Hezbollah has not signed this paper. Iraqi militia factions have not signed this paper,” Hassan said. “Tehran has committed to using its leverage to bring them into compliance, but leverage is not the same as command and control.”

U.S. Central Command confirmed late Wednesday that one rocket had been launched from western Iraq toward a base in eastern Syria but had fallen in open desert, causing no casualties. The Iraqi government condemned the launch and pledged an investigation. No other incidents had been reported by early evening Washington time.

Officials in Islamabad said a follow-on round of talks aimed at sequencing prisoner releases, war-cost accounting and the eventual reopening of Iranian airspace to commercial traffic would begin Saturday, with American, Iranian, Israeli, Saudi and Egyptian delegations expected to attend. A senior State Department official said additional confidence-building steps would be announced “in the coming days as the verification mission reaches operational footing.”