Bringing up Saddam’s old victims to excuse the 100,000+ deaths caused by the Iraq war is one of the most absurd arguments I’ve seen. The war did not stop any large scale murder - those were victims of the past murder committed under very specific circumstances and there was no evidence whatsoever that Saddam would start any large scale massacres in the future (and that wasn’t even one of the reasons given for the invasion; as HRW noted, it was not a humanitarian intervention). There is simply no a posteriori justification for the Iraq war, no matter how much anyone wants to be among “the good guys”.