I would like to suggest a new halakhic category of war.
We are familiar with:
– Mandatory war (מלחמת מצווה) – with the aim of clear self-defense (still applicable) or of defeating the violently oppressive nations identified in the law (no longer applicable).
– Discretionary war (מלחמת רשות) – with the aim of expanding the political jurisdiction of the Torah (only applicable with an active National Court).
To these I would add:
– Forbidden war (מלחמת איסור) – with any aim other than the above two.
I believe this third category of war is implicit in the biblical precept of “You will not murder” (לא תרצח) and is not explicit in the halakhic literature or discourse primarily because historical and material circumstances did not previously allow for the conditions in which it would need to be so pressingly articulated, and secondarily because it took millennia for humanity itself to recognize war as the (necessary?) evil it is and for this moral growth to natively and organically develop within the Israelite psyche.
However, we find ourselves in the present circumstances, and I believe the hour requires us to include the category of “forbidden war” in our halakhic calculus.