WASHINGTON/DUBAI, 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 ports of its Gulf neighbours after weekend talks on ending the war broke down. Oil prices climbed back over $100 per barrel, with no sign of a swift reopening of the Strait of Hormuz to ease the biggest ever disruption in supplies and broader concerns over the durability of a two-week ceasefire agreement reached last week. Trump said that Iran had been in touch on Monday and wanted to make a deal but that he will not sanction any agreement that allows Tehran to have a nuclear weapon."Iran will not have a nuclear weapon," Trump told reporters at the White House. "We ca...