New Delhi, April 15 -- U.S. President Donald Trump has raised the stakes in his showdown with Iran after declaring the American military has blockaded all of the country's ports.

Trump announced the move on Monday, a day after ceasefire talks with Iran in Pakistan ended without agreement.

The blockade is part of an effort to force Iran to open the Strait of Hormuz to global traffic and accept a deal to end an inconclusive war that has inflicted heavy damage on Iran, reverberated across the region and shaken the world economy.

Iran, however, responded with threats against all other ports in the Persian Gulf and the Gulf of Oman, raising the possibility that the two-week ceasefire declared last week could collapse and the war could resum...