Peace is a spiritual realization of seeing the underlying reality of non-duality. Once we come upon this depth of spiritual insight or revelation and you see without doubt the oneness and unity of all mankind; that you and I are one, then your actions will be informed by this awareness.
Aikido then takes on a different quality than it had previous. We'll still defend ourselves from attacks and aggression the best way we can (say we go to war to take down Hitler) but now our whole perspective have changed. It has been informed by greater insight into the nature of non-dual reality. As such your reactions will be different and you will see your Aikido advance and maybe you will begin to see what O Sensei meant when he said all those things of being one with the world. Those enlightening moments did change his expression of Aikido.
All I'm simply saying is this, there is a reality behind the concept of Peace that is mind-blowing and profound and it is possible to acquire such an understanding through sincere and relentless pursuit thereof. It is part of the spiritual seeking that will bring you home to your self. Hopefully O Sensei leads the way to inspire us to walk this path of non-violence.