McCain is right; it could have been avoided. If, in the aftermath of 9/11, President George W. Bush had treated the arguments of Feith, McCain, and other advocates of the Iraq War with the disdain they deserved, we (and the Iraqis) wouldn’t be where we are today.Iraq is imploding because Sunni and Shiite have warred against each other for more than a thousand years. This is what Islam does.
So, yes. Put the blame where it belongs. Some of it on a president who didn't know and didn't learn but had to do something in light of 9/11. (And he was right about Saddam's "stockpiles.") Pile a more generous helping on his successor who, being the "smartest president ever" and a(n allegedly) former Muslim, must have known what would occur but abandoned anyway gains made in Iraq at unfathomable cost in blood (and treasure).
But the bulk of the responsibility for the current "mess" in Iraq goes to the ideology that motivates so much death and destruction: Islam.