And why do the Iranians do this? Because they can. Because the Iranians know the US has the weakest leader in history who bows down to them, who will be more than happy to pay them more money, OUR MONEY, to avoid conflicts they started.
If we had a stronger Commander in Chief he/she would have given the order to blow one of these Islamic Revolutionary Guard Corps dinghies out of the water. This would be followed with 1-2 carrier battle groups parked right out in front of Iran with a statement that any further actions will be considered an act of war.