We have seen earlier that some actions during the Second World War that could be defined as war crimes or crimes against humanity may have been investigated but were not prosecuted in international courts in 1945. In some instances this was because those who were responsible were now perceived by the post-war superpowers as potential allies in the Cold War. But many of these actions against civilian populations or unarmed prisoners of war were carried out by the victorious allies. The perpetrators were not brought to trial and in some cases the actions were not perceived at the time by the Allies to be war crimes. Indeed these remain controversial issues in the former Allied powers and historians are often divided about the legality and morality of what happened.
There were also cases of US and Australian troops executing surrendered Japanese prisoners of war and US and Canadian troops executing German prisoners of war. French Moroccan troops killed Italian prisoners after the battle of Monte Cassino. In a number of countries that had been occupied by Axis forces there were reprisals and counter-reprisals between partisans (or resistance units) and those who had collaborated with the occupiers. There were also numerous corroborated accounts of atrocities by Soviet troops and mass deportations in the Baltic States, Finland and eastern Poland after the signing of the German-Soviet non-aggression pact in 1939 and again after the German withdrawal and Soviet advance in 1944-45.