Training Risky, just because nations were allowed to get away with various genocides in the past does not excuse them from paying fair and proper reparation now. Holding nations to account for crimes is just as important as holding individuals to account.
If nations were obliged to pay reparations for unjust wars in a systematic fashion, then the USA should have paid reparation for the invasion of Vietnam. If they had been obliged to pay reparations for the war crimes they committed in Vietnam, you can be sure there would be a lot of entirely innocent Iraqis and Afghans still alive today. They (and us) may have also hesitated in invading Iraq on an equally fabricated and unnecessary premise if they were obliged to pay reparations if their justification for the invasion was proven incorrect (which was the case - no WMD).