I think some people are missing the point, you are thinking war where we sink Iranian ships , send in a bunch of carriers and it is all over, this isn't about that kind of threat. Iran is located next to the main pathway the ships must travel, along that route the path the tankers must follow narrows to a distance of just 34 miles. 34 miles might seem like a lot but also consider the tankers cannot use that entire opening, instead they use about 5-6 miles of it. Iran doesn't have to stage an all out war to cripple that pathway, they can send 1 plane a day to drop bombs and that will end shipments. Would you as a tanker captain even entertain the idea of carrying millions of gallons of oil, highly flammable, through an area that is targeted ? Or Iran can mine the entire area requiring it to be cleared taking months to complete.