There are never many 'just wars' or at least wars fought on 'just' and moral reasoning. Even WW2 was not a moral war for the Brits, as we didn't give a damn about anything other than our own self interest.

A just war, in my opinion, is one agreed via the UN on humanitarian grounds. In the modern world, that can be the only way a war should be justified.

Though it would probably help if we didn't arm everyone to the hilt with our weapons.