The President of the United States, Donald Trump, said on Wednesday that he had “instructed the United States Navy to shoot down and destroy any and all Iranian gunboats if they harass our ships at sea”.

The president’s statement on Twitter came a week after the Pentagon accused Iran of sending 11 fast boats to conduct “dangerous and harassing approaches” to six American warships in the Persian Gulf.

The Iranian vessels, according to the Defense Department, “repeatedly crossed the bows and sterns” of the American ships at high speed, coming within 10 yards of one ship.

Nearly a dozen vessels from Iran’s Islamic Revolutionary Guard Corps Navy took “dangerous and provocative” actions near U.S. Navy and Coast Guard ships in the Persian Gulf, the Pentagon said last Wednesday.

Six U.S. military vessels were conducting training operations in international waters when 11 Iranian ships “crossed the bows and sterns of the U.S. vessels at extremely close range and high speeds,” according to the U.S. Navy statement.

The U.S. crews issued multiple warnings via bridge-to-bridge radio, five short blasts from the ships’ horns and long-range acoustic noise devices to the Iranian ships.

“After approximately one hour, the IRGCN vessels responded to the bridge-to-bridge radio queries, then maneuvered away from the U.S. ships and opened distance between them,” the statement added.

Hours after the incident, Secretary of State Mike Pompeo said the administration was evaluating a response.

“We’ve seen this before, where the Iranians behave in ways that were inconsistent with international law,” Pompeo said.

He said the U.S. was “evaluating how best to respond and communicate our displeasure with what took place.”