It's been described by abductees as having to do with an evolved telepathic awareness of the life forms around them, which (I think) makes sense in an evolutionary way because all evolution is a process of life forms forming and reacting to the environment and then growing more and more able to effect the environment and other life forms around them -- a logical extension of "mind to matter"(thoughts and plans which are then put into play with physical effort) is the mind/thought becoming more linked to the environment.

so if you're a species with interconnected minds and awareness of all of each other's thoughts/intents/etc. -- then there can be no real "war" because both sides know what the other is planning, what they want, why they are doing what they're doing, there can be no "winning" when both sides know everything about the other side and their plans/capabilities/etc.

when you reach a certain level of technology, one that humans are scratching the surface of right now, you can't "go to war", you HAVE TO be peaceful because both sides can simply destroy each other or prevent their own destruction using (for example) anti-missile missiles or ABM defense shields, so no one benefits from conflict and the only way to benefit is mutual respect and distance from each other, or cooperation, which is what many abductees say is happening.

makes sense to me. any species who is not on that level might be ignored, studied, or taken over by a more advanced civilization -- in which case the more advanced civilization would have no need to "go to war" because the lesser species would have no means to defend themselves adequately anyway, so the advanced species can use the lesser however they choose.