Martin Luther King Jr. was against the Vietnam War because he realized the very prospect of war in modern times lead to great injustice–especially when waged by the US against smaller third world nations. I suspect King would be seriously disappointed by US and Russian involvement in Syria.
During recent months I have come to see more and more the need for the method of nonviolence in international relations. While I was convinced during my student days of the power of nonviolence in group conflicts within nations, I was not yet convinced of its efficacy in conflicts between nations. I felt that while war could never be a positive or absolute good, it could serve as a negative good in the sense of preventing the spread and growth of an evil force. War, I felt, horrible as it is, might be preferable to surrender to a totalitarian system. But more and more I have come to the conclusion that the potential destructiveness of modern weapons of war totally rules out the possibility of war ever serving again as a negative good. If we assume that mankind has a right to survive then we must find an alternative to war and destruction. In a day when sputniks dash through outer space and guided ballistic missiles are carving highways of death through the stratosphere, nobody can win a war. The choice today is no longer between violence and non- violence. It is either nonviolence or nonexistence
–MLK Jr, “Pilgrimage to Nonviolence” (1958).
We must find some alternative to war and bloodshed. In a day when man-made vehicles are dashing through outer space, and guided ballistic missiles are carving highways of death in the stratosphere, no nation can win a world war. It is no longer a choice between violence and non-violence; it is either non-violence or non-existence. The alternative may well be a civilization plunged into the abyss of annihilation, our earthly habitat transformed into a tragic inferno that even Dante could not imagine. So this is our challenge: to see that war is obsolete, cast into limbo.
I do not wish to minimize the complexity of the problems to be faced in achieving disarmament and peace. But we shall not have the courage, the insight, to deal with such matters unless we are prepared to undergo a mental and spiritual change. It is not enough to say we must not wage war. We must love peace and sacrifice for it. We must fix our visions not merely on the negative expulsion of war, but upon the positive affirmation of peace. We must see that peace represents a sweeter music, far superior to the discords of war. Somehow we must transform the dynamics of the world power struggle from the negative nuclear arms race which no one can win to a positive contest to harness man’s creative genius for the purpose of making peace and prosperity a reality for all of the nations of the world. In short, we must shift the arms race into a peace race.
— MLK Jr, “Remaining Awake Through A Great Revolution” (1965)