Wars today are different from wars fought in earlier times. It was part of our Evolution, just like animals, we attacked each other for materialistic gain. Today, the situation is similar but today the beneficiaries of a War might be much more limited, such as the leaders of a political entitiy. To say if a war is just or not, you need to understand which war u're talking about. For a Palestinian, attacking Israel is very Just, but in the West, anything as such is called "Terrorism". Similarly, after 9/11, most americans thought that Afghan and Iraq wars were just because they saw their fellow citizens being killed. But now most of them don't find the War so just because they're paying billions of dollars for it.