How to prevent war?

How to prevent war? This is the very complicated question but we can find its roots. The roots are because of human mindset.
Another reason is because human beings create it by killing. According to Buddha, human beings have many life in the past, not just one life. So, in the past life, if we had committed many sins, we could be born in different places like hells or became animals, ghosts, etc. For those who had done many good deeds, they might born in heaven or human again.
According to Buddha, killing animals or another human beings can lead us to the hell or became ghosts or animals. This is call retribution.
So, in order to prevent getting killed, we have to stop killing.
Whether you believe it or not, I think no killing is ready good. I had not killed any animals for quite sometimes. In the past, especially in my younger age, I was quite naughty and hurt many animals including bees, etc.
Now, I had adopted a non-violence attitudes towards animals and human beings. Recently I attended the meditation talk, the teacher was telling audiences that we should not kill ants unnecessarily. That mean we can not just simply kill ants because all beings are scared to death. How can we give fear to them unless we want to be killed in war, accident.
Yes, now I adopt the peaceful means and my life is become so peaceful. I was more healthy than before because I never give fear to anybody now.
By reading the topic above, we should know how to prevent war?