Evolution of a darker, deeper post that will probably get five comments

So, I'm watching X-Men: The Last Stand (review posted below). In case you've never seen one of these films, it involves mutants of various "skills and features" frequently in conflict with the humans (like us today) and usually at the instigation of the latter. It's a rather obvious metaphor for The Holocaust and people being persecuted and killed for being different.

I'm telling my friend Sara about this comparison, and somehow it came up that our government responded with the proclamation that we would never allow something like that to happen again. Not on our watch. We start talking about how it has happened in Cambodia, Bosnia, Iraq, and central Africa, and now Darfur is in the headlines for these types of atrocities where thousands of people are being senselessly murdered.

And then I'm watching The Man Who Shot Liberty Valance because one of my dear bloggers suggested it during a Q & A post practically a year ago. At one point, Jimmy Stewart makes a comment about how conversation isn't particularly effective when someone brings a gun to it (I couldn't find the exact line on IMDB, unfortunately).

So, I ask: can diplomacy realistically be used in situations of genocide (esp. given the frame of mind of those who commit these acts)? Has it ever been?