There can be no peace without war. There will always be communists and terrorists in the world that are hellbent on messing up the world. There are 2 options:
1) Keep the 'world peace' idea, let them do what they want, and watch the world destroy itself on CNN.
or
2) Stop them and restore order.
Sure, war is ugly, but it is necessary. World peace is a great idea, but it is unachievable. The whole, "War is wrong, let's all like each other" stance is impossible. People will always disagree with each other and there will always be differences and tension amongst our fellow human beings. It is inevitable.