It's pretty obvious that we were the bad guys here
The aliens crash landed on our planet and were trying to get home when we attacked them.
The first sailor made initial aggressive physical contact with their ship and it's first act was to create a defensive force field perimeter. They don't attack non-threatening entities and we humans have an instinctive fear of the unknown as a life-preserving defense mechanism......so we shot at them. Only problem was that they were stronger and better prepared to defend themselves than we thought. In almost every instance from initial contact, when we stop attacking them, they stop attacking us. That's not the posture of an invasion force. Also, they board the Navy vessel to steal parts and energy to help repair their own ship so they can leave the planet.
Watch it again from that perspective, that they were shipwrecked on a hostile world full of violent beings, and you'll watch the movie completely differently.
http://them0vieblog.com/2012/04/13/we-come-in-peace-shoot-to-kill-battleships-truly-alien-alien-invasion/
http://www.armchairgeneral.com/forums/showthread.php?t=127907
My religion is very simple. My religion is kindness. - The Dalai Lama