> The reality is that whether the war in Iraq was justified or not is a completely separate discussion, and the US going to war with Iraq (whether justified or not) is not a justification for Russia going to war with Ukraine.

This. If all we do is justify our current actions with the past, then every country can find some historic argument for invading another country. So yes, US in Iraq means nothing for Russia attacking Ukraine, it is a red herring by Putin propaganda. It is just hard or impossible to convince those who believe in it.