US President Donald Trump’s order for the US to attack Iranian gunboats is the latest sign that an asymmetrical war-fighting strategy is stymieing the world’s mightiest navy, with US aircraft and destroyers forced to track swarming speedboats in a vital energy waterway.

“I have ordered the United States Navy to shoot and kill any boat, small boats though they may be,” Trump said Thursday in a social media post, claiming that those vessels are laying mines in the Strait of Hormuz.

The target – Iran’s so-called “mosquito fleet” – has been known to US officials for years and weapons testers have regularly evaluated new warships’ ability to counter it. During tensions in 2020, Trump instructed the US Navy to target “Iranian gunboats” harassing US vessels.

Trump’s order undercuts the administration’s repeated claims that Iran’s navy has been decimated. White House press secretary Karoline Leavitt played down the threat of Iran’s “speedy gunboats” in a Fox News interview on Wednesday, insisting the US has destroyed Iran’s conventional naval capabilities.

It also leaves unanswered questions around the extent of Iranian mine activity, which US Central Command has declined to detail. The size of the Islamic Revolutionary Guard Corps’ small-boat fleet also is unclear, with a 2019 Defence Intelligence Agency estimate citing hundreds of such vessels across the Persian Gulf.

US strikes may have damaged Iranian command-and-control “too much to allow dedicated, comprehensive minefields,” said Steve Wills, an analyst with the Navy League’s Centre for Maritime Strategy.