War crimes The records of the war crimes trials after World War II provide one of the most comprehensive formulations of the concept of war crimes. During that war the Allies agreed to try Axis war criminals. In Aug., 1945, Great Britain, France, the USSR, and the United States established a tribunal at Nuremberg to try military and civilian Axis leaders whose alleged crimes were directed at more than one national group. The trial opened in Nov., 1945. Voluminous evidence was presented to prove the plotting of aggressive warfare, the extermination of civilian populations (especially the Jews), the widespread use of slave labor, the looting of occupied countries, and the maltreatment and murder of prisoners of war. Among those sentenced to death (1946) were Hermann Goering , Joachim von Ribbentrop , and Julius Streicher . Hjalmar Schacht and Franz von Papen were acquitted. The court did not convict Nazi organizations or the German general staff. In 1961, Israel captured, tried, and later executed Adolf Eichmann .     A trial of 28 alleged Japanese war criminals was conducted (1946-47) by an 11-nation tribunal in Tokyo. Evidence similar to that presented against the Nazis brought death sentences to Hideki Tojo and others. The U.S. Supreme Court refused an appeal that was based on the ground that the international court was unlawful. There were many trials in national civil and military courts, including those of the Japanese generals Tomoyuki Yamashita and Masaharu Homma.     Critics have questioned the legal basis of some of the charges at the post-World War II trials. Individuals were found guilty of acts considered legal, or even required, by their nation at the time; such findings represent a violation of the concept of sovereignty . The plotting or carrying out of aggressive war had not been previously and explicitly called criminal, and the judges tended to define it very narrowly. A defendant was generally found guilty only if he had been involved in developing the policy, but not if he had simply carried it out.     Critics have also termed the trials an act of vengeance by the victors and questioned their practical use as a precedent. Personal liability for national action is very difficult to prove conclusively, and a nation will be reluctant to try its own leaders. Therefore, effective prosecution may be possible only if a nation is defeated (and then perhaps only if the documents are captured, as they were after World War II).     Both critics and supporters of the U.S. role in the Vietnam War have justified their positions on the basis of the post-World War II trials. Several Americans were tried for war crimes in this war, and Lt. William Calley was found guilty (see My Lai incident ) of particularly disturbing acts against civilians that for many became emblematic of the horrors of the Vietnam conflict. In the 1990s, in reaction to war atrocities committed by various parties during the breakup of Yugoslavia , the United Nations established a tribunal in The Hague, the Netherlands, and attempted to gather evidence for prosecutions; Serbs, Croats, and Muslims have been charged, including top civilian and military Bosnian Serb and Bosnian Croat leaders. The highest ranking official to be tried is former Yugoslavian president Slobodan Milošević , whose trial began in 2002. In 2000 the Hague tribunal officially established rape, which was rampant during the Yugoslav civil strife, as a war crime. A UN tribunal was also set up in Tanzania to try those responsible for Hutu massacres of Tutsis in Rwanda in 1994 and in Sierra Leone to try persons accused of atrocities in that country's civil war (1991-2001).     Despite increasing international recognition of the need to prosecute war crimes, such offenses are still often unpunished. Although there have been many calls for prosecution of former Khmer Rouge leaders for war crimes, they have not tried by Cambodia or internationally (due mainly to the failure of the Cambodian government to reach an agreement on trials with the United Nations). In Indonesia the national courts have tried a number of Indonesian officials and officers for war crimes in East Timor during 1999, but the proceedings have mostly ended in whitewash acquittals.     In 1998 the UN General Assembly voted in favor of a treaty authorizing a permanent international court for war crimes. The United States, China, and five other nations opposed the treaty, and 21 nations abstained. The treaty has been signed by more than 130 nations (including the United States), and formally came into effect in July, 2002; the judges of the court were formally sworn in in 2003. Called the International Criminal Court and located at The Hague, it may prosecute war crimes, genocide, crimes of aggression, and crimes against humanity. Under the G. W. Bush administration, the United States opposed implementation of the treaty, out of fear that American officials or military personnel might be arrested abroad on baseless charges. In May, 2002, the United States repudiated its signing of the treaty and indicated that it would refuse to cooperate with the court; it subsequently insisted that U.S. forces used as UN peacekeepers be exempted prosecution by the court.