Trump ramps up the rhetoric

Tweet from Trump:

I have instructed the United States Navy to shoot down and destroy any and all Iranian gunboats if they harass our ships at sea.

I don't think he's referring to harassing navy ships here but US ships in general. The thing is, how many ships are flying a US flag in the Strait of Hormuz? I imagine this is all posturing but this tweet haunts me:

Trump ramps up the rhetoric