WASHINGTON: US President Donald Trump said Wednesday he had ordered the US military to attack and destroy any Iranian vessel that harasses US Navy ships.

"I have instructed the United States Navy to shoot down and destroy any and all Iranian gunboats if they harass our ships at sea," Trump said on Twitter, just hours after Tehran launched a satellite.

The order came one week after 11 small armed Iranian Revolutionary Guards Corps speedboats swarmed around US Navy and Coast Guard ships in international waters in the northern Gulf.

The incident took place while the US vessels were engaged in exercises as part of their patrols in the region.

No shots were fired, but the Pentagon said the Iranians engaged in "dangerous and provocative actions" that risked collision or worse.

The Iranian Revolutionary Guard Corps boats "repeatedly crossed the bows and sterns of the US vessels at extremely close range and high speeds," coming at one point within 10 yards (nine meters) of the bow of one.

The much smaller IRGC Navy vessels ignored warnings from the US ships for about one hour, before finally responding to radio communications and then leaving, the US side said.

On Sunday, the Revolutionary Guards accused the US Navy of "unprofessional and provocative behavior" that had interfered with their own exercises, according to Mehr News Agency.

Trump's statement followed Tehran's announcement Wednesday of its first successful launch of a military satellite.