Hold on a minute. JW's aren't pacifists. They simply don't recognize the sovereignty of nations.
Where there is the draft, pacifists have the option to register as "conscientious objectors" and have themselves assigned to non-combative roles. As I understand it, JW's are not encouraged to take this option. Which seems stupid to me. It means jail and "martyrdom".
As for pacifism itself, I wonder if it isn't a question of how big is your tribe. If your tribe is the whole world, then why would you take up arms against your neighbour?