President Donald Trump on Thursday said he has ordered the U.S. Navy “to shoot and kill any boat” that is laying mines in the Strait of Hormuz.

“There is to be no hesitation,” Trump wrote in a Truth Social post.

The president added that he is ordering U.S. minesweepers to continue clearing the strait “at a tripled up level!”

The post shows the U.S. ratcheting up tensions with Iran over the vital oil-shipping route, which has been largely choked off since the war began in late February.

Trump has aggressively pushed Tehran to fully reopen the strait as part of a shaky ceasefire, which was set to expire this week before being unilaterally extended by the president.