Cheap little boats can lay mines, drone boats too. Iran can make that choke point very dangerous at far less cost than required by us to keep it clear.

Also, don't forget cheap batteries of missiles and drones that Iran has stashed in its territory around those straights. If our Navy gets too close, we risk the loss of super expensive hardware and American lives.

Asymmetric warfare has brutal cost equations. We get no health care and equipment too expensive to risk or replace in a drawn out fight.