Tony Adragna has a thoughtful post about the philosophy of war. The essays that he mentions are "Terrorism and the Philosophers - Can the ends ever justify the means?" and "The Moral Limits of Strategic Attack" and raises some good points. This is principled pragmatism at its finest - honest discussion of the moral issues regarding using violence as a means. There's plenty of room for disagreement here but these essays (and Tony's post) are definitely required reading.