India, April 14 -- The US military began a blockade of ships leaving Iran's ports on Monday, President Donald Trump said, and Tehran threatened to retaliate against its Gulf neighbours' ports after weekend talks in Islamabad on ending the war broke down. Trump said Iran had been in touch on Monday and wanted to make a deal but that he would not sanction any agreement allowing Tehran to have a nuclear weapon. "Iran will not have a nuclear weapon," Trump told reporters at the White House. "We can't let a country blackmail or extort the world."

A U.S. official said there was continued engagement with Iran and forward motion on trying to get to an agreement. Pakistani Prime Minister Shehbaz Sharif also said efforts were still under way to re...