In a retrospective article on the Russian-Georgian conflict, Lewellyn Rockwell discusses Washington's attempt to resurrect WWI-era rhetoric. He quotes a 1915 book written by Francis Neilson, "How Diplomats Make War":
"During a war it is no easy task to prevent your sympathy clouding your reason. The whole social system seems to be organized against any individual attempt to concentrate the attention dominantly upon the causes of the war. Governments, churches, theatres, the press, and local authorities, direct their efforts, in the main, warwards; the whole thought of society and commerce seems to be occupied with war; and all desire to question the reasons given by statesmen for participating in the war must be suppressed. It has been ruled already by certain 'leaders of thought' that it is unwise, unpatriotic, and un-English, to suspect the motives of Governments, or waver for a moment in swearing wholehearted allegiance to the authorities: you must think only of the war. If you dare ask for the truth, you are helping the enemy; if you suggest an early peace, you are hindering the militarists who desire no peace until their enemy is utterly crushed. Insidious, bewildering, and plausible, are the reasons given by statesmen and journalists for inflicting a humiliating defeat; without it, they tell us we must not hope for disarmament. No patriot is supposed to ask if disarmament is at all probable. No one must ask if a single statesman really believes such a blessing will follow if the enemy be annihilated."
What is particularly interesting about this Russian-Georgian conflict is that it is ultimately about preventing secession - the Georgians attempting to prevent South Ossetia, Abkhazia and other provinces from seceding. I am particularly interested in the link between pacifism and secession.
Ask yourself, if a nation has to use military force to keep a political region unified, isn't that an indication that there's something wrong? You could argue that there may be moral imperatives that justify use of military force to maintain unification, as in the Civil War, but there are serious complications with this position. Should any state have the right to make war on any other state for perceived immoral activities? If so, and states acted on this right, the world would be in a constant state of war. Even more important, if governments have a duty to use military force, if necessary, to prevent the violation of certain moral principles (as in the case of slavery), should they not apply this right consistently or not at all? If the state only punished murderers of a certain race, we would consider this unjust - the government doesn't have a right to not punish certain criminals on the basis of some arbitrary metric, such as race. If the US government has a moral duty to prevent the occurrence of slavery, then by what standard of justice do we apply this moral duty only to certain states (e.g. the Confederacy) but not others?
In short, if a smaller body politic wishes to secede from a larger body, I cannot think of any good moral justification for the use of military force. Every such artificial unification is ultimately imperialistic in nature. It seems to me that pacifists need to rethink their (usual) support for ever more centralized governments and ask whether every local region should have the right to peaceably and without molestation secede from the larger political organization to which they belong. If so, then pacifists should oppose US support of Georgia (and the implied threat of military force to protect her) and her oppression of the South Ossetians and Abkhazians who simply wish to live in their own, independent state. They speak different languages, for goodness sake.
As an aside, I think that a crucial element of human psychology on which imperial resistance to secession depends is the hubristic conviction of most individuals that they - or their identity group - know the way it oughtta be. If people just did things our way, why, there wouldn't be so many problems in the world. It's OK that my nation subjugates other, more ignorant and backward nations because we are tutoring them on how to run a civilized, decent human society. The Romans said exactly the same thing.
So, to those who oppose war (who doesn't oppose war?), I ask: How do you justify the use of military force to prevent secession? I just don't see it.