>> On Friday, Pope Francis ruled out the possibility of “just wars,” saying they do not exist.
The pope is actually correct on this. The just war *theory* describes when it is all right to engage in war and revolves around issues of national defense and proportionality.
In this way, no war is just, in and of itself. Only one side in a war —if either— can be said to have entered justly: the war itself is never just.
Thus we can say that one nation in a war aggressed against the other, which is not just. The other side *justly* defends itself against the unjust actions of the other.
The Pope should read St. Thomas Acquinas.