@RYNO87 Sea units can never attack territories containing whatever defending units.
In other editions battleships and cruisers under special conditions can support amphibious assaults by shore bombardment, but not in this game.
I believe subs can move on non combat movement into a sea zone with hostiles, but can any other sea unit?
No other sea unit can do that. Rulebook page 20:
"Sea Units
A sea unit can move through any friendly sea zone. It cannot enter a hostile sea zone during this phase.
Submarines: Unlike other sea units, submarines can move through and even into hostile sea zones during this phase.
However, a submarine must end its movement when it enters a sea zone containing one or more enemy destroyers."
@Panther great thank you!