I think the torpedo will have issues reaching the ship. So you have a missile moving at, let's say, mach 2 sea level, it drops the torpedo. Assuming it does not get destroyed by impacting the water, will it even enter the water, or will the speed be too much for it to even go below the water for the next few x kilometers. Assuming it goes under the water when the missile drops it, it will have to deal with enormous friction at that speed.
I say create AUVs, put them in the shores of the Persian Gulf and upon order make them do slow silent one way missions to all ships they encounter. This would be a good size:
