War crimes are breaches of international rules that limit the means and extent of violence in armed conflicts. These rules are based on a combination of international treaties and laws, as well as the principles that underpin humanitarian law. A broad range of acts is considered a war crime, including rape and sexual violence, killing civilians and POWs, and using torture, forced displacement and bombing to achieve military objectives. The term ‘war crimes’ is attributed to a book published in 1906, though the idea that certain weapons and behaviours were out of bounds during armed conflict dates back to ancient times. The atrocities committed by Germany and Japan in World War II helped to establish the conception of a war crime as a serious breach of international law and prompted the establishment of tribunals that dealt with these offences after the end of the war.
Previously, individual soldiers and commanders were rarely prosecuted for their actions in war. Instead, the victorious nations simply ignored the horrors committed by their enemies or prosecuted their own troops for their role in the war. This changed after World War II, when the mass murder of millions of people – mainly Jews but also other groups – by Nazi Germany and the mistreatment of prisoners of war and civilians by the Japanese army led to the Nuremberg trials and the creation of international tribunals such as the ICTY in The Hague for crimes committed during the wars in the former Yugoslavia.