The west has tried to blame the escalating sectarian murders and impending civil war on the Iraqi peoples, whether it be Sunni against Shia or vice versa. this is a major tragedy that the "freeing" of Iraq should have foreseen.
This tragedy should have been anticipated.
I blame America and Britain.
There will be a massive bloodbath in Iraq. The west can do nothing to stop it now, But we should have never caused it.
Our governmental intransigence has forced this situation to overwhelm Iraq by our unending occupation.
We all know who is to blame. Shame on us for causing this situation.
But most of the shame goes to Blaire and Bush for allowing the situation to escalate further until a time when they mutually leave office.
They won't care then, they are no longer involved.

Or do you think there is another reason why Britain will leave Iraq first, around the time of our elections. then shortly followed by America, Some time later.
Guess which country has it's election first.

Just a hypothesis, never a conspiracy. you need at least 2 for that.