(Reuters) – President Donald Trump on Tuesday reimposed a naval blockade of all Iranian ports and threatened to hit power plants and bridges next week unless Tehran resumes negotiations, in the U.S. escalation of the conflict.

The U.S. also began a fresh round of strikes “to continue degrading Iranian capabilities used to attack commercial shipping in the Strait of Hormuz,” the U.S. military said.

Tehran says it has again closed the strait after hostilities between Iran and the U.S. reignited last week, fraying an already fragile truce reached in June after several months of fighting that has killed thousands.