Michael Ignatieff's mea culpa on his support for the Iraq war can be found here
Ignatieff's line is that as an academic he was too interested in ideas, and didn't have the horse sense he's subsequently developed in the political trenches. I think that's disingenous. Ignatieff was never really a theorist: he was an academic politician, and from the very beginning his cause was humanitarian war.
When he's prepared to consider the problems with that construct, it will be time to listen.