Note: The following is an extract from the book “Bechayil Uve'Ruach,” by Rabbi Chaim Drukman zts"l, a leading figure of Religious Zionism for many decades.. The title of the book hints at the verse, “Not by might nor by power but by my spirit, the God of Hosts says” (Zecharia 4:6). The army of Israel applies this principle, as it fights - “By might – with the spirit of God.”
(A) Milchemet Mitzvah (Obligatory War)
In Chapter 5 of Hilchot Melachim (Laws of Kings), the Rambam explains that according to Jewish law, there are two types of wars in Israel: Milchemet Mitzvah (a war that is a positive obligation) and Milchemet Reshut (a permitted war). A king of Israel must first perform all of the required wars before he is permitted to go to war for discretionary reasons.
The Rambam lists three types of wars that fall under the category of Milchemet Mitzvah:
"What is considered an obligatory war? The war against the seven nations, the war against Amalek, and the defense of Israel from an enemy that attacks them."
Unfortunately, the third type—"the defense of Israel from an enemy that attacks them"—is highly relevant in our times, as many enemies still seek to harm us.
It is clear that the Rambam agrees that there is a mitzvah to fight in defense of the Jewish people. In fact, it is difficult to imagine anyone disputing this, since it is well-known that one may violate the Sabbath to save even a single Jewish life. If that is the case, then how much more so is it a mitzvah to fight in order to protect the collective life of all of Israel!
In our time, all halakhic perspectives agree that we are obligated to wage a Milchemet Mitzvah due to the commandment: "to defend Israel from an enemy that attacks them."
I addition, there is a halakhic ruling that one must go out to battle even on the Sabbath if enemies approach a border town, even if they are only coming over a dispute on straw and hay, because such incidents could ultimately lead to an invasion of the land. This law is codified in the Shulchan Arukh as a practical legal guide for our times—making it clear that the mitzvah to fight remains relevant today!
We must recognize that this message is valid for all generations, especially for our own. We must ensure our survival and strength—not because we want to fight, for the true aspiration of Israel is the opposite of war and bloodshed. However, at times, we have no choice. We are required to fight in order to exist, so that we may ultimately bring the moral and just values of Torah to all of humanity and thereby bring true happiness to the world.
(B) The Obligation to Participate in National Life




