according to the ufopedia, we already know aliens are attacking (which is why they created us) so its more of patrol mission.
as for the tech demo my two cents, why make a stiletto at all? its not about interception. i like the scenario i read here, here is my take on it:
1.starts the same with peaceful town (from here each part picks up the pace)
2. show our blue beauty from space, mother(carrier) ship pops to view from behind the camera, passing with engines roaring, sending "scouts" to earth (btw i dont recall anything about motherships or carrier in ufopedia)
3. we see the same radar screen with udo poping on screen (only its radar room on our base) then the alarm goes off, red light etc, running soldier boots in the coridor (easier than full models) and stilettos take off from the runway.
4. here there is no need for a movie just skip between good pictures of a dog fight(some thing for the imagination) with last one shwing alien ship goes down.
5. here we are slowing down, showing an alien hesitantly going out of the ship streching this part and then bamb he got shot by phalanx troop.
6. zoom on his phalanx patch ....
and if you want to be real cheesy put the inception sound track