At the end of W.W.II, the US actively sought out the scientists of Nazi Germany, and from Japan (unit 731, the Ishii unit). Certain generals decided that it was much more important to have the information that these scientists derived from the torturous experiments that each committed against the subjected, conquered populations of the regions they'd occupied, and on some of the prisoners of war, than to try them for war crimes. The US brought hundreds of these scientists to the US, or hid them under the auspices of the allied occupation forces, and allowed them to remain free. Some went on to positions of extreme power and wealth in exchange for the results of their insidious research programs.
2. War crimes are among the grossest of human rights violations. However in any dispute the response to them changes in the final stages of the conflict. Priorities change and moral absolutes lose their sharp edge. Rights violations that earlier seemed totally unacceptable and deserving of the most rigorous condemnation start to be candidates for reassessment at the bargaining table. But such crimes cannot be left unexamined without mocking justice in places where they were committed and without inviting repetition of such violations in other locations.
2. Trials of enemy officers are a mask for summary execution. Their very possibility aggravates cruelty in the conduct of wars as no concept of decency and honour on the battlefield is left.