When you are serving in the IDF you are not invading other countries, you are serving to protect yourself, your family, your neighbors, and your land. One would think from these Hareidim that if the Nazis were invading Poland in 1939 and they knew in retrospect that the Nazis would throw them in concentration camps, that the Hareidim would accept their fate because "God told them not to fight" and not serve in fighting against the Nazis!
Serving is self-defense. Self-defense is Pikuach Nefesh and permitted by halacha. If you are a pacifist, then do National Service outside of the IDF. You think secular high schoolers know any more how to hold a gun than yeshiva students before basic training?! If the IDF tells you to invade (Gaza, Lebanon, etc.) then refuse orders on the basis of morality if you so believe. But DON'T condemn the draft!