President Donald Trump said he has ordered the U.S. Navy to “shoot and kill” any vessels laying mines in the Strait of Hormuz, escalating tensions with Iran over the key global oil route.

He also directed minesweeping operations to be expanded “at a tripled up level” and claimed the U.S. has full control of the waterway.

The Strait, which normally carries about 20% of global oil shipments, has seen traffic drop sharply amid conflict and restrictions linked to the ongoing crisis.

The U.S. has imposed a naval blockade, turning back dozens of ships, while Iran has largely shut down the passage in response, CNBC has reported.

Iranian officials insist the strait will remain closed under current conditions, as diplomatic and military tensions continue to rise.