"This is a very dangerous and reckless thing to do and it is brinksmanship that has great potential for miscalculation," Daly said on Thursday. "After warning shots, if the commander on scene believes there is hostile intent, the unit will take the targets under fire."
One of the US warships subjected to the harassment, the Squall, fired warning shots in the direction of the approaching Iranian vessels causing them to turn away.
"All US warships have an inherent right to self-defense,” Daly added.
The surface combatants Tempest, Nitze and Stout also used communications and set off flares to wave off the Iranian fast boats.
Cook also said Iranian actions risk escalating tensions between Tehran and Washington if they fail to conduct themselves professionally.
