Donald Trump has declared that the strait of Hormuz will be “completely open” from Friday, as western leaders gathering at the G7 summit in Évian-les-Bains battled to prevent the fragile US deal with Iran from almost immediately unravelling.“The deal’s all signed. And the strait ⁠is already partially opened,” Trump said as he arrived at the summit in France, but Israeli breaches of the ceasefire in Lebanon and Iran’s claims about its right to charge fees in the crucial waterway revealed the agreement’s many loose ends.Speaking at the start of bilateral talks with the French president, Emmanuel Macron, on Monday, Trump rejected a proposed UK-France joint naval mission in the strait, saying “I don’t think we will need much help” keeping it open.“I think a lot of great things are going to happen in the Middle East right now. And very importantly, the oil is plummeting down and the stock market is shooting up like a rocket today,” Trump said. “The main thing is that Iran will not have a nuclear weapon. They fully agreed to that with strong policing powers, and they won’t have a nuclear weapon, which is what it was all about.”Trump says Iran deal has been signed – videoThe memorandum of understanding – which US officials said would open the strait of Hormuz in exchange for a lifting of a US naval blockade on Iran – is set to be formally signed at a ceremony in Geneva on Friday attended by the US vice-president, JD Vance, and the chief Iranian negotiator, Mohammad-Bagher Ghalibaf.White House officials said the full details of the agreement would be published in the next 24 to 48 hours.But the G7 leaders gathering for three days of talks found themselves already trying to shore up the agreement that the US had signed.Technical discussions led by Vance from the US side will begin later this week, including the more thorny issues of the fate of Iran’s nuclear programme, which Trump has declared must never be able to produce a nuclear weapon.It would also include provisions to lift sanctions and unfreeze billions of dollars in frozen assets, but US officials said that would be tied to “Iran meeting their commitments”. They insisted no Gulf country was cutting a side deal to unfreeze Iran’s assets, but suggested the US was “prepared to release frozen funds, and we are prepared to relieve sanctions”.“We’ll do some small gestures of that in the beginning, if they make some small gestures to us that show that they’re willing to meet their commitments,” another official added.They declined to provide specifics on what that “small gesture” would be, but the first official later clarified that as of now, “$0 of unfrozen assets have been released by the United States or any other country”.The administration officials also said that there would not be an immediate drawdown of US forces near Iran upon the signing of the MOU.“The plan is to keep the current force posture during the … negotiations in force,” the official said. “We hope to draw them down. We’re not doing that yet. We want to see the Iranians do what they promise.”An Israeli strike hit the village of Srifa, southern Lebanon, after the announcement of the preliminary deal. Photograph: Wael Hamzeh/EPAFriedrich Merz, the German chancellor, said the deal could stabilise the world economy, but warned Israel that the ceasefire agreement must apply to Lebanon. He spoke after an Israeli drone targeted a vehicle in southern Lebanon killing one person, the second death since the 60-day ceasefire was agreed.Ursula von der Leyen, the European Commission president, warned: “There can be no lasting peace whilst Lebanon remains in flames.”In Israel, concern and anger deepened during the day, directed at both Trump and Benjamin Netanyahu, the Israeli prime minister. Analysts and commenters quickly pointed out that none of Netanyahu’s promises at the beginning of the war in February – which included regime change in Tehran and the destruction of Iran’s nuclear programme – had been fulfilled.Israel has also launched a wide-ranging offensive into Lebanon after Hezbollah, which has close links to Iran, fired missiles at northern Israeli towns during the first week of the war, suffering new casualties against an enemy that had been previously dismissed by officials as no longer posing a serious threat.Opposition politicians were quick to capitalise on what some local media described as an “abject failure”. Far-right members of Netanyahu’s ruling coalition called for Israel to ignore the agreement, saying it had not been party to negotiations.The national security minister, Itamar Ben-Gvir, said of the memorandum: “Trump’s agreement does not bind us … We must not settle for anything less than the dismantling of Hezbollah. We must not withdraw from a single inch of territory that our soldiers have captured and cleared.”