Full Idea
To Aquinas's three conditions for war (Idea 7291) modern theorists have added two others: that to be just a war must have a reasonable chance of success, and that the means used to conduct it must be proportional to the ends sought.
Gist of Idea
War must also have a good chance of success, and be waged with moderation
Source
A.C. Grayling (Among the Dead Cities [2006], Ch.6)
Book Reference
Grayling,A.C.: 'Among the Dead Cities' [Bloomsbury 2006], p.212
A Reaction
These two principles strike me as being much more civilized and humane than Aquinas's original contribution, suggesting that in our theoretical thinking we might be making some progress.