There's one thing that's always bugged me about X-COM style games. We have ways to meet threats on the air, threats on the ground but not a way to meet threats via the sea. Call me crazy, maybe I've been playing a bit much Harpoon but I think that naval forces are one of the most overlooked things in these style of games. Consider this:
In this era, cruisers outfitted with the Aegis system and its precursors, along with aircraft carriers could intercept UFOs.
Carriers can serve as mobile bases of sorts, allowing insertion via helicopter or landing craft. If I'm not mistaken, a nuclear powered carrier can steam to a hotspot within a matter of hours. You could transfer personnel, weaponry and aircraft to them. They could have a small radar system and allow some variety in response.
Battleships (if for instance, a mission is on a coastline) could fill in for a heavy vehicle and lay down indirect fire. Of course, range would have to be limited. Could be possible to penetrate a UFO's exterior.
Opinions, fellow 'nauts?