DARN IT!! How do you tell what nation they are??

[Sailor Steve]

The point is that they then place neutral ships inside enemy convoys, and kaleuns who sunk ships in convoys were given credit, no matter who the ships belonged to.

Setting neutrals to '0' still means you wasted torpedoes for no gain, so it's still a good idea not to do it if it can be avoided; but if they're in a convoy you shouldn't have to worry about losing credit for doing your job properly.