Missile Submarines can't attack boats?

[Lightning Hunter]

Why is it that RA won't let me use Missile Submarines to attack enemy gunboats?  It gives me the "x" symbol.  Oddly enough, if I force fire one square away from enemy boats, the missiles will damage them...  Is this a bug, or intended?  I never really used missile ships much in the past.  In fact, I am embarrassed to say that I never played all the Aftermath missions until now.

Edited May 13, 2017 by Lightning Hunter

[nariac]

Just the way it works. They wanted you to use normal submarines to support your missile submarines. Although force-fire lets you get around that a bit.

Players also force fire with cruisers to destroy submarines instead of escorting the cruisers with destroyers/gunboats.

[Jacko]

Very fun things start happening if you use guard mode with them though, they can even attack aircraft.