Penalty

As long as our society has a penal system, I think any politician who gives the order to go to war, for whatever reason, should be sentenced to jail. At the very least, he should stand trial. Think about it - if someone kills only one person in self defence, he must face up to his actions in a court of law. Why should a man who orders the death of thousands go free with no questions asked?
A man can give such an order with absolutely no risk to himself, and even if it becomes clear, after the war is over, that his (I use the masculine pronoun for simplicity) reasons for starting it were wrong, he can simply shrug his shoulders and say "I was wrong", and then move on with his life. And probably a quite confortable life at that.
To be honest, I do not think punishing crimes is the best way for a society to fight it, but as long as we have that system, it should be consistent. In my opinion, murder is always morally wrong. I cannot think of a single instance where it could be considered completely right, though in some instances, as in the defence of one´s own or someone else´s life, the use of deadly force is understandable.
I said in the beginning that I think a man should be punished for starting a war even if it is considered to be a fair war for noble reasons. I say this because I think such a decision should not be taken idly. If you truly feel such a thing is absolutely necessary, you should also be prepared to face the consequences. A terrorist who plants a bomb believes his motives justifies his actions, and he knows that if he gets caught, he will be punished. He is prepared to face those consequences. The same should be true for a statesman.