The Talmud has always had a moderating influence on the Hebrew Bible and it has been claimed that this accounts for the virtual pacifism of Ashkenazic Jewry up until the creation of Modern Israel. These arguments on whether people can be drafted for wars that do not answer imminent threats do not seem arcane, but downright current, as Rabbi Menachem HaMeiri (1249-1306) comments on a Talmudic dispute:

Where the rabbis and Rabbi Yehuda argue is in the case of a pre-emptive strike where we are fearful of the enemy that they may strike us, or that we know they are preparing to strike us. According to the sages, this is considered an obligatory war, and anyone engaged in the war is absolved from fulfilling other commandments while Rabbi Yehuda considers that as long as the enemy has yet to attack, it has to be an authorized war and one is not absolved from fulfilling other commandments.

Meaning that if someone is engaged in a sacred task, he cannot be drafted for this type of war. The Torah itself allowed for a type of conscientious objector–one who did not have the stomach for it. If your interested in a survey of the literature, and powerpoint click here