I have always found interesting the question of why countries go to war? Obviously, if you need to defend yourself you don't have too many options. But why the

I have always found interesting the question of why countries go to war? Obviously, if you need to defend yourself you don't have too many options. But why the elite of a nation will start a war will all the consequences and the danger of loosing territory. Of course, this elite believes they will never suffer the consequences of war. That's why nuclear weapons are a terrifying deterrent. However, something I read recently was very illuminating: every time somebody decides to go to war, believes it is going to be short and quick. You don't start a war when you don't believe you have a clear advantage. We can also see that many times this thought was wrong and led to lengthy with a high cost on human lives.