For The Guns of Navarone, I wonder if a star system containing a gas giant with several habitable moons might make a suitable setting? Anything attempting to approach Moon 3 (your territory) must by definition come within range of Moon 2 (enemy territory), not to mention that the newly-constructed super gun on Moon 2 threatens Moon 3 itself.
Or, instead of a super weapon, perhaps the target is a super sensor array. Use the plot from Navarone, but you're attacking the equivalent of a radar station, making it the equivalent of the real live raid on Bruneval. While you're at it, take a look at Two Men Went To War, in which two men stage their own unofficial raid on a German radar station, not achieving much on their own and probably only surviving because a genuine Commando raid on the same station just happened to be going on at the same time - the sort of coincidence which nobody would accept in a work of fiction, but this film is based on a true story.
You could also try The Eagle Has Landed. Your heroes have to kidnap, or failing that kill, an enemy leader. They're disguised in enemy uniforms but wear their own uniforms underneath so that, if something goes wrong, they fight under their own colours and won't be executed as spies. Something goes wrong... Or, turning it around, the characters are in a small settlement which finds itself host to an army unit on an exercise, but something happens to give the game away - the unit are actually enemy infiltrators who lock down the settlement, and now the players must figure out how to get a message out to a nearby genuine army base. Also consider Went The Day Well, with a vaguely similar plot. The Eagle Has Landed takes the side of the German infiltration team; Went The Day Well, being a British wartime propaganda film, most definitely does not!