Several issues have been raised that have bearing on the civilian question. These include:
- The deliberate targeting of "enemy" civilians.
- Combatants posing as civilians;
- Combatants sending civilians into a known targeted sites to act as "shields";
- Civilians choosing to go into known targeted sites to act as shields; and
- Combatants choosing high density civilian areas and structures from whence to perform military operations and store munitions.
- Planting explosives near civilians to maximise damage by enemy fire.
Intention is important. One can argue whether or not an army deliberately targeting civilians is legitimate in war. The West generally condemns this action as morally wrong. While I am in general agreement with this, one could make an argument that it may be dependant on the choices "enemy" civilians make. But if we accept that intentional targeting of civilians is immoral then those who do so carry the guilt even if they are unsuccessful in their intent. That is, if they miss the target or strike the target but it has been evacuated such that no one is killed, the intent and attempt at civilian death is present. They should be thought of and treated similarly to any other group which accomplishes intentional civilian massacre. The lack of achievement of their goals does not remove their culpability.
Conversely, an attack that targets combatants yet also kills some civilians should be assessed based on the underlying intent. If the target is legitimate and attempts are made to minimising civilian death (while still achieving the objective) then these are unfortunate casualties of war. One can argue that minimisation was not done adequately such that civilian deaths were excessive for the particular objective, but it is difficult to argue that important targets cannot ever be targeted for risk of civilian death; if that is the case then the risk is all militarily important persons and equipment will be placed within these regions.
When the military chooses civilian infrastructure that civilians are using or are near to, such as hospitals, schools, churches, mosques, etc., then they are placing their own people at risk. If they are doing so in an attempt to minimise their enemy's response or maximise the moral outrage of allies when civilian deaths are publicised then they are making a strategic decision, but one that carries significant responsibility—the responsibility for the lives of those civilians. Whatever the guilt, or lack thereof, for the death of these civilians it lies primarily with the combatants and their commanders who have acted in this manner. There may be situations where opposing troops end up in populous regions but this is a different situation.
The moral responsibility for the death, injury or even risk when civilians are forced to act as human shields is clearly those doing the forcing. Though given that such civilians may switch allegiance in this situation it would be prudent for the opposing army to take this into consideration with regard to long term strategy.
However civilians who act as human shields voluntarily are in a different situation. One can argue how "voluntary" the action is, which is a legitimate concern; but in situations where civilians are doing this of their own volition they are actively participating in the war. They are not just choosing a side—many civilians are on the side of their own army, though not always—they are joining the battle and thus it could be argued that they have become combatants and as such are as legitimate a target as any soldier. Their blood is on their own head.
Combatants posing as civilians carry significant moral responsibility. Whereas a combatant hiding amongst civilians may be thought cowardly; one who disguises himself as a citizen such as a labourer, a merchant, a woman; or as a humanitarian worker such as an aid provider, a nurse, a doctor; while actively fighting places those people at risk. The reason for this is that they will subsequently all be seen as possible combatants. If 3 of 10 emergency food truck drivers are combatants who engage the enemy from this position, how is the enemy to know that the other 7 are not also combatants? If the real aid workers end up dead in the engagement then the blame is with the disguised combatants, not their enemies who fired the fatal bullets.
Lastly, intentionally increasing the death toll of your own citizens for propaganda purposes scarcely needs commenting on.
All this does not have significant bearing on the justice of one's cause nor the rightness of engaging in war. If your cause is wrong, even if you avoid civilian casualties, your cause is still wrong. If your cause is right, you can still make right and wrong decisions in how you seek your cause. We must be careful not to justify evil behaviour because we agree with the cause.