Gandhi stressed that the means and the ends are inseparable. If we want a nonviolent world, we cannot get there by supporting invasion and occupation, nor even "lightly armed peacekeepers," as we often hear UN troops described.
Nonviolence is a matter of faith, no matter how much empirical evidence we amass to show its efficacy, because hypotheticals can always be posited to demonstrate how naive and callow it is to have such simpleminded ideas. In the end, we either go with a nonviolent approach to conflict and we figure it out or we eventually say, well, I guess we'll have to make this exception and that exception. Once we do, our potential adversaries will not trust our commitment to our putative method, and who can blame them?
So our very faith in nonviolence is part of what makes it strategic; when we reduce the fear of physical attack on the opposition we make our own people more safe, which is exactly backward from what many assume about nonviolence, and they have their own points too.
"Well," they might assert, "what about the guileless Native Americans who were so badly abused when they offered nonviolence and hospitality to the English and Spanish who came across to plunder? So much for friendliness and nonviolence."
Good point. Just two comments in response.
One, Native Americans had no reported strategic plan to bolster their hospitality. Should they have? Of course not; they had a culture and in their context, what they did was quite adaptive and effective. They simply were up against an alien force--undocumented at that.
Two, Gandhi hadn't taught humankind that there was a strategic nonviolent response to injustice and violence. All our violent responses pre-Gandhi were all we knew as a species; either violence or surrender.
For those who are pacifists, violence never works as a fallback, as a last resort, or as "when all else fails" plan. This is a major challenge to those who claim pacifism, and there are no guarantees; on the other hand, where are the guarantees with the violence of police, of missiles, of 'defensive' arms? In every violent contest, there is at least one loser and often the Pyrrhic nature of violent victory really creates two or more losers.
In the end, we hope, we can continue to amass a growing success rate with nonviolence so that peace will become the default setting, at least human-to-human. Humanizing ourselves and all others is the first step toward victory with our opponents, creating partners where there used to be adversaries.