The premise of the movie is basically
Independence Day!
Earth is being invaded by aliens that act as a hive and move from planet-to-planet wiping out the resources before moving on. They are ultimately defeated by blowing up a nuclear device in the heart of the alien command structure and in order to get there the humans had to mask themselves as the aliens to avoid destruction. Right before the nuclear device goes off a close-up shot of an alien is shown showing that they quite don't understand what is about to happen. The heroes barely escape the explosion but escape they do.