Jus ad bellum: Appropriate reasons to enter into war
self-defense
defense of others
human rights
Jus in bello: ethical conduct in war
protection of non-combatants
suffering of the population should be mitigated
proportionate violence
"the use of this barbarous weapon at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender.… in being the first to use it, we…adopted an ethical standard common to the barbarians of the Dark Ages. I was not taught to make war in that fashion, and wars cannot be won by destroying women and children.”-- Adm. William Leahy
Hiroshima, 1945