All of the data indicates that the earliest followers of Jesus were pacifists and would have identified with Gandhi's answer. The stories of the martyrs include many instances where individuals willingly gave their lives and watched as family members gave theirs without returning violence for violence. After Constantine it became clear to those in power that pacifism was no longer an option. They believed that empires required armies and the threat of death so the theologians went to work to build a schema that would allow for the possibilities of state sponsored violence and would define under what circumstances killing was allowed or even required. They came up with the "Just War Theory."
Augustine was the first theologian to propose a just war framework and set the tone for the discussion from then on. His framework was
Principles of Just-War Theory
1. Last Resort
A just war can only be waged after all peaceful options are considered. The use of force can only be used as a last resort.
2. Legitimate Authority
A just war is waged by a legitimate authority. A war cannot be waged by individuals or groups that do not constitute the legitimate government.
3. Just Cause
A just war needs to be in response to a wrong suffered. Self-defense against an attack always constitutes a just war; however, the war needs to be fought with the objective to correct the inflicted wound.
4. Probability of Success
In order for a war to be just, there must be a rational possibility of success. A nation cannot enter into a war with a hopeless cause.
5. Right Intention
The pirmary objective of a just war is to re-establish peace. In particular, the peace after the war should excede the peace that would have succeeded without the use of force. The aim of the use of force must be justice.
The violence in a just war must be proportional to the casualties suffered. The nations involved in the war must avoid disproportionate military action and only use the amount of force absolutely necessary.
7. Civilian Casualties
The use of force must distinguish between the militia and civilians. Innocent citizens must never be the target of war; soldiers should always avoid killing civilians. The deaths of civilians are only justified when they are unavoidable victims of a military attack on a strategic target.
Other expressions of the Just War Theory also included a proscription against destruction of property, specifically the burning of structures.
Certainly that framework has formed the basis of moral justification of military violence since and the argument makes sense even if some of the criteria, especially #2, may seem a bit dated. I would argue though that there has never been a war that met those criteria. That is not the point of today's post.
Seventy years ago, the US dropped the first atomic bomb on Hiroshima followed a few days later by the second on Nagasaki. The argument goes that Japan was planning to execute all prisoners of war and that a ground war in Japan would have cost many more lives that the conservative estimate of 135,000 (mostly civilian) deaths from the dropping of those two bombs.
If we begin with virtually any iteration of the Just War Theory, the bombings were simply immoral. The number of civilian deaths and the complete destruction of two cities is simply not acceptable according to any Just War theory. To equate the deaths of civilians to that of military is never allowed. Even if those civilian deaths did save the lives of Allied military forces, it is still immoral according to Augustine's argument. That a second bomb was dropped was even more repugnant.
My local paper had an editorial today arguing that the bombings were both necessary and good. That the writer felt that argument needs to be made is telling. It also feeds the continued growth of nuclear weaponry as the argument states that there are times when the use of such horrible weapons is justifiable. The lesson we must learn from the bombing of those two cities is that the use of weapons of mass destruction is simply immoral under any circumstances and the world must work in concert to rid ourselves completely of all nuclear weapons.