Orianna Fallaci nails it:

It remains for the reasons I will try to state. And the first one is that, contrary to the pacifists who never yell against Saddam Hussein or Osama bin Laden and only yell against George W. Bush and Tony Blair, (but in their Rome march they also yelled against me and raised posters wishing that I'd blow up with the next shuttle, I'm told), I know war very well. I know what it means to live in terror, to run under air strikes and cannonades, to see people killed and houses destroyed, to starve and dream of a piece of bread, to miss even a glass of drinking water. And (which is worse) to be or to feel responsible for someone else's death. I know it because I belong to the Second World War generation and because, as a member of the Resistance, I was myself a soldier. I also know it because for a good deal of my life I have been a war correspondent. Beginning with Vietnam, I have experienced horrors that those who see war only through TV or the movies where blood is tomato ketchup don't even imagine. As a consequence, I hate it as the pacifists in bad or good faith never will. I loathe it. Every book I have written overflows with that loathing, and I cannot bear the sight of guns. At the same time, however, I don't accept the principle, or should I say the slogan, that "All wars are unjust, illegitimate." The war against Hitler and Mussolini and Hirohito was just, was legitimate. The Risorgimento wars that my ancestors fought against the invaders of Italy were just, were legitimate. And so was the war of independence that Americans fought against Britain. So are the wars (or revolutions) which happen to regain dignity, freedom. I do not believe in vile acquittals, phony appeasements, easy forgiveness. Even less, in the exploitation or the blackmail of the word Peace. When peace stands for surrender, fear, loss of dignity and freedom, it is no longer peace. It's suicide.

Some people believe that no war is just. I disagree, but it a deeply held conviction to them. I also think it's naive, was WWII just? The American Revolution? When people are oppressed by torture, murder, and rape, do we not owe them the opportunity to live free? I believe we do. Read the whole thing.