Final answer:
The statement that war must be a last resort is true and aligns with the principles of just-war theory, which evaluates the moral justifiability of war.
Step-by-step explanation:
The statement that war must be a last resort aligns with just-war theory, which is a set of criteria used to determine the moral justifiability of a specific war. This theory includes principles like the legitimacy of the cause, the declaration of war by a proper authority, the right intention behind the war, the probability of success, and the war being fought as a last resort after all other options have been exhausted. The notion of war as a last resort is paramount in ethical discussions about when war might be morally justified. The ongoing assessment of harm versus benefits, as mentioned by Lazar (2018), is crucial to maintaining the just status of a war over time.