A small missile might damage or disable a ship but not sink it.
I wonder why there are no ultra long range torpedos, some sort of “intercontinental torpedo” which are are to operate pretty much like a drone over distances of thousands of miles. These would be larger and not be launched from tubes but launched like a small boat. Using a slow cruise mode to catch up and then homing in at very fast speed. Given you could make em a lot bigger you might even use them for damaging harbors and other coast based installations.