US President Donald Trump has warned American forces could resume strikes against Iran within days, even as Vice President JD Vance said negotiations over Tehran’s nuclear programme have made significant progress.Mr Trump said on Tuesday that he recently called off a planned US attack, but left the door open to renewed action.“I hope we don’t have to do the war, but we may have to give them another big hit,” he said. He added that any decision could come within a narrow window of “two or three days – maybe Friday, Saturday, Sunday, or early next week".Mr Vance struck a more cautious note, saying talks had made “a lot of progress” and suggesting Tehran could still agree to a deal. But he also warned military action remained “option B” if negotiations collapsed.The war, which began on February 28 with US and Israeli strikes across Iran, has disrupted energy flows from the Gulf and strained global shipping routes. A fragile ceasefire has been in place since April 8.Iran has maintained a stranglehold on the Strait of Hormuz, a critical global energy route, and has resisted US demands to fully dismantle remaining nuclear infrastructure despite facing attacks.In Washington, resistance to further escalation appears to be growing, with the Republican-led Senate advancing a procedural vote on a resolution aimed at ending hostilities. Iranian Foreign Minister Abbas Araghchi warned on X that any renewed conflict would bring “surprises", referring to Iran’s claim that it downed an F-35 fighter jet. “With lessons learnt and knowledge we gained, a return to war will feature many more surprises,” he added.'Red line'Regional tension escalated further at the weekend after a drone strike caused a fire near the Barakah nuclear power plant in Abu Dhabi. The UAE said on Tuesday that the drone was launched from Iraqi territory.The UAE's ambassador to the UN, Mohamed Abushahab, told an emergency Security Council meeting on Tuesday that attacks on nuclear plants were a “red line”. He added that his country reserved the right to defend its territory under international law.Diplomatic efforts to end the conflict continue on several fronts. Chinese President Xi Jinping called for an immediate end to hostilities during talks with Russian President Vladimir Putin, who arrived in Beijing on Wednesday for a state visit.Chinese President Xi Jinping with Russian President Vladimir Putin in Beijing. EPAInfoEnding the war would help stabilise energy supplies and global trade, Mr Xi said. “It is imperative to stop the fighting," he added.Mr Putin's state visit follows recent trips to China by Mr Trump and Mr Araghchi, as Washington and Tehran remain deadlocked over the Strait of Hormuz and efforts to turn the ceasefire into a lasting settlement.Meanwhile, two Chinese supertankers carrying about four million barrels of crude from the Middle East reportedly exited the strait on Wednesday after weeks of delay. Deliveries are expected in China in early June.