U.S. military is poised to blockade Iranian ports, while Tehran threatens ports in the Mideast  CTV NewsU.S. military’s promised blockade of ships leaving Iranian ports expected to begin shortly  CBCU.S. blockade of Strait of Hormuz set to begin  CNBCIran threatens Middle East ports as U.S. military set to impose shipping blockade  The Globe and MailU.S. naval blockade taking effect as Trump demands Iran end nuclear program  The Washington Post