But why do soldiers and their officers still commit war crimes and crimes against humanity in the 21st century when they know that these are contrary to the Laws of War and International Humanitarian Law and that they risk facing a military tribunal at home or may be accused by the International Criminal Court?
As we saw in this case study of the massacre at Monte Sole, forces in retreat through what they perceive as enemy territory may terrorise the local civilian population to isolate them from resistance and guerrilla forces and even treat the civilians as if they were all potential combatants. Commitment to racist ideologies also motivated some troops to commit atrocities against those whom they regarded as inferior peoples: a tendency which has also been observed in several conventional wars and civil wars since 1945.
However, another factor that needs to be taken into consideration is the training of soldiers. According to Dr John Tirman of Massachusetts Institute of Technology, a study of US soldiers in World War II showed that less than one in five ever fired their weapons during the conflict. After the war military training was changed to address this. In the Vietnam War 90% of US soldiers fired their weapons and this change has been sustained ever since. There has been much more emphasis in their training on killing the enemy. An important part of this is the need to dehumanise the enemy to overcome the human reluctance to kill other humans. While they receive some training in the rules of military engagement this is far outweighed by the training in combat.