What is a "just" war? Can war and warfare - combat - be judged separately or together?

Why attempt to identify and examine the differences?

Consider the Second World War, for example.

Was declaring war against Imperial Japan justified? Of course; Japan attacked us and killed over 3,000 of our sailors, airmen, soldiers, and civilians at Pearl Harbor.

Were our actions in combat, strategically and individually, justified? This causes us to look at the island-hopping campaigns as well as the strategic bombing campaign and both the implications and results of each.

If we do not examine these issues, as individuals and as nations, we set ourselves up to repeat our mistakes.