War and the military machine.
There are a number of indirect references to the second world war which suggest that it was inspiration for this movie.
The movie isn't glorification of war, instead part of it's message seems to be about the increasing desensitisation to violence. It isn't a major concern if you get stabbed or injured (even during training), just call for a medic.
This movie is one that you will either like or hate, I do actually like it.
Not an overly complicated plot, it isn't trying to tell a story, more of a reflection on society and where we are heading. However, the plot goes something like this. One way to become a citizen with some rights is through the military.
What do the military want? What they have always wanted, more power, and young men/women fresh out of high school. Hence they are encouraged to join up and do their bit.
What the new recruits don't know is that they will soon be fighting in a full scale war against alien insects.