President Donald Trump said warship USS Spruance fired on Iranian cargo ship TOUSKA for breaching a blockade in the Gulf of Oman.
Iran's ambassador to Pakistan Reza Amiri Moghadam condemned the action, accusing the US of violating international law and escalating the blockade.
Iran rejected a second round of talks, citing US 'excessive demands' and the naval blockade, while US officials hinted at military action.
Trump said a US delegation, led by Vice President JD Vance, will travel to Islamabad for negotiations.