The US military said Sunday it would begin a blockade of all Iranian ports within hours, after peace talks in Pakistan collapsed with Washington blaming the Islamic republic's refusal to abandon its nuclear ambitions.

The announcement came despite a ceasefire agreed on Wednesday aimed at pausing the six-week war until April 22, with tensions centered on whether the United States can force Iran to reopen the strategic Strait of Hormuz, another of its key demands in the stalled negotiations.

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