In Battleship, the aliens wear helmets that enhance their vision by highlighting things in either green or red. It is quite clear that green things are deemed harmless while red things are threats.
Not unlike the predators, it looks like the aliens are very careful not to harm harmless things and refrain from attacking anything which is not a threat. However, this rule does not always apply. Among others:
- Cannons on the destroyers become red as soon as they are aimed toward the aliens, but the machine gun on the small boat only becomes red when it is fired at them, not sooner.
- Several people become green as soon as it is clear they are not armed or don't attack the aliens (e.g. the kid in the stadium), but Hopper stays red even after he is disarmed and is trying to escape.
- Some objects immediately become red (e.g. the pillars of the bridge) even though they are harmless.
I fail to see the logic in that. If the aliens wanted to conquer earth, they would use their powerful firepower to destroy everything, regardless of their nature. If on the other hand they were mere scouts whose mission was to send a message home, they would not initiate conflict and use their formidable shield as a shelter while they wait for reinforcements.
Am I missing something?