ISLAMABAD, April 13 -- President Donald Trump on Sunday said the U.S. Navy would "immediately" begin a blockade of ships entering or leaving the Strait of Hormuz, after US-Iran ceasefire talks in Pakistan ended without an agreement or next diplomatic steps in sight. In his first public comments after the 21-hour talks, Trump sought to eliminate Iran's key source of leverage in the war by exerting strategic control over the waterway that was responsible for the shipping of 20% of global oil supplies before fighting began. A US blockade could further rattle global energy markets. It was not immediately clear how it might be carried out, but Trump told Fox News the goal was to ensure all ships could transit: "It's going to be all or none, and that's the way it is." Trump said he has "instructed our Navy to seek and interdict every vessel in International Waters that has paid a toll to Iran. No one who pays an illegal toll will have safe passage on the high seas." Other nations would be involved in the blockade, he said, but did not name them. Freedom of peaceful navigation is a basic principle of international maritime trade, but Iran has asserted control of the strait. In Iran, meanwhile, state media reported that navy special forces have deployed to the southern coast, signalling readiness for a potential invasion by American troops. Iran's Revolutionary Guard later said the strait remained under Iran's "full control" and was open for non-military vessels, but military ones would get a "forceful response," two semi-official Iranian news agencies reported. During the talks, the US military said two destroyers had transited the strait ahead of mine-clearing work, a first since the war began. Iran denied that. Trump stressed that Tehran's nuclear ambitions were at the core of the talks' failure, and the US was ready to "finish up" Iran at the "appropriate moment." In comments to Fox News, he again threatened to strike civilian infrastructure and said he was fine with his widely criticized threat before the ceasefire that a "whole civilization will die tonight." The face-to-face talks that ended early Sunday were the highest-level negotiations between the longtime rivals since the 1979 Islamic Revolution. Both delegations later left Islamabad. Neither indicated what will happen after the ceasefire expires on April 22. Both said their positions were clear and blamed the other. "We need to see an affirmative commitment that they will not seek a nuclear weapon, and they will not seek the tools that would enable them to quickly achieve a nuclear weapon," Vice President JD Vance, leading the US side, said afterward. Parliament speaker Mohammad Bagher Qalibaf, who led Iran's side, said it was time for the United States "to decide whether it can gain our trust or not." Iranian officials earlier said talks fell apart over two or three key issues....