Is there a way to force units to ONLY use depth charges?

[artao]

I'm making a scenario in which i don't want "enemy" units to use anything but depth charges against the player, even if they have other weapons available. i.e. - "semi-neutral" surface craft trying to drive the player out of Soviet territorial waters, without actually killing the player.
Is there a way to do this?
I'm still trying to figure out doctrine and script languages.

Thanks!