DN--It gets complicated if you're talking about conscription...though personally I believe that in very, VERY extreme circumstances it's necessary. But these days, especially with modern tech, I think we'd be talking World War III bad before that necessity ever came about. And if it got that bad, I would be volunteering, even though as a woman I am not required to put myself on the draft list.
(The draft list itself is an interesting question. We haven't used the draft in YEARS and I don't think it would happen except in extreme emergency, but I do find myself thinking that perhaps women should be required to register as well, like is done in Israel.)
For me, there is a difference between being the aggressor and being the defender. If you are the aggressor, then I definitely see your argument. If you are the defender...I believe STRONGLY that there is a moral duty of defense, and that here, it's failure to act on behalf of others if you are capable of it that is the biggest problem. If you just let the aggressors act unchecked, then two things are happening. Others die in your place, and those who cannot defend themselves may die because of your inaction, and those lives are then on you if you had the ability to act and did not.
I recognize that a pacifist, for instance, will believe it is better for ALL--the potential soldier, and those he/she would have defended, to die than for one man to take up arms. But to me...I simply cannot adhere to that position and believe that I am living up to all of my moral duties and obligations.