There is a commandment to make two special silver trumpets. They were used to give instructions to the camp in the desert as to when it was time to travel. There is a verse that is interpreted to be prophetic, related to these trumpets, known as חצוצרות. It speaks of a major war that will signal the final battle of Gog and Magog, that will herald the coming of the Mashiach.
The Torah speaks of a battle with “הצר הצורר אתכם,” the enemy that is oppressing you. The Rambam explains that this term is related to the definition of what is a מלחמת מצוה, translated as a defensive war, or a war that is a Mitzva to fight.
Unlike the other war that requires the permission of the Sanhedrin, known as מלחמת רשות, the Milchemet Mitzva reflects battles that depend on our survival.
The Milchemet Reshut is requested to expand borders. The Milchemet Mitzva has three categories. The first is the war we are expected to wage against the archenemy of the Jewish people, Amalek. It also includes the commandment to drive out or destroy the “Seven nations” living in our land, preventing holiness to enter. These first two categories are probably not applicable today, but the third, definitely is.
The Rambam defines הצר הצורר אתכם as referring to a group that is living in our midst, that wishes to drive us out of our land. Therefore, it is under the category of Milchemet Mitzva, to do whatever is necessary to make sure that they do not fulfill their intentions.
We must constantly remind ourselves that we must seek the Torah to guide us in every aspect of life. We are to make the will of G-d, our will, and we must act in a way that will find favor in His ways.