Why Was The Trojan War Unjust?

I think that the Trojan war was unjust, there was no reason to start the war in the first place. Wars are supposed to be the last resort of action, only to be fought when there are no other options. Wars also need a valid reason to start. Just because a lady gets kidnapped doesn't mean that the whole country should be put at risk, forcing the men to fight. The biggest reason the war was unjust is that the whole thing was because of the gods. The gods were being unfair to the mortals because they brought the people into the mess, they should have settled it by themselves.
Wars should only be waged if there is no other option. The Greeks should have tried other methods before starting the war. They could have killed Paris and taken Helen back