Given how Berg seems to base his premise on the idea that any contact with an alien species might be inherently harmful, no matter what our (or their) intent, and the minimum development and focus on the aliens, it is possible the whole conflict was a gigantic misunderstanding. After all, the Americans fire the first shot - albeit a warning shot - leading the aliens to respond in force. When the aliens do respond with force, they are initially more concerned with disabling infrastructure rather than causing harm. One alien avoids killing a kid, and another repeatedly pushes a human aside, rather than killing him.