EXOD623 The Talmud introduces a new category of war, however, and claims that Rabbi Judah and the Sages disagreed about that [i.e., whether wars waged by the Kings of the House of David for the purpose of territorial expansion were discretionary, and that the wars waged by Joshua for the conquest of the land of Canaan were required by God]. The category consists of wars “to diminish the heathens so that they shall not March against them.” M. Sotah 8:7 (44b). According to the Talmud, because such wars are not specifically commanded by God in the Bible, Rabbi Judah and the Sages agreed that the biblical exemptions [to military service] apply, but they refer to such preemptive strikes in different terminology because they disagreed on their status and other matters. The Rabbis included such wars in the general category of discretionary wars because they are not specifically mandated by God in Scripture. Rabbi Judah thought that even though that is the case, preemptive strikes of the sort described nevertheless fulfill a commandment because they are necessary for self-defense. In other words, even though the Torah does not specifically require such wars, it indirectly commands that we engage in them as part of the general biblical obligation to defend yourself based on Exodus 22:1, which exonerates a householder who kills a burglar. (Compare B. Sanhedrin 72a and Yoma 85b). Rabbi Judah, therefore, described wars of self-defense as “commanded wars” (milhamot mitzvah) and invented a new term, “obligatory wars” (milhamot hovah), to mark wars that are specifically required by God in the Torah, such as the conquest of Canaan. The practical result of this disagreement, according to the Talmud, is based on a general principle, according to which a person who is engaged in the performance of any commandment is exempt from the fulfillment of other commandments during that period. For Rabbi Judah, since preemptive wars constitute a commanded act, soldiers engaged in them may take advantage of this exemption; for the Rabbis, though, such wars are discretionary, and the soldiers engaged in them are still obliged to fulfill all other commandments. In sum, the conceptual structure of the Mishnah and its talmudic commentary distinguishes two, and perhaps three, types of war: specifically commanded wars, including the wars against the seven Canaanite nations (for example, Numbers 31:7, 15f. and 33:55 and Deuteronomy 7:2, 20:16f) and the wars against Amalek; Exodus 17:14-16 and Deuteronomy 25:17-19). Discretionary wars, including the wars of King David to expand the borders of Israelite territory; and, for Rabbi Judah, indirectly commanded wars, including preemptive wars for purposes of “diminishing the heathen so that they will not March against them [the Israelites].” For the rabbis, the last of these is simply another example of discretionary wars, but for Rabbi Judah they constitute a separate category of “commanded” wars.