This isn’t that hard. They fire a few rockets & damage a few tankers. Then the people who own and insure said tankers stop sailing through that particular body of water because the risk is just too high when you consider the extent of their investment. A few ships went through because either they a) coordinated with & probably paid the Iranians, or b) thought the warring parties were actually serious about a “ceasefire” (they weren’t). To sum it up, Iran can hold significant sway over the strait, even if they’ve been reduced to a limited number of crude weapons.