re: I have as much evidence against it as you have for it.
It woud be interesting, though likely impossible, to find out how many of the "insurgents" were drawn from the Iraqi populace.
You have to admit that the US wasn't particularly well liked by many in the Middle East, and especially among the politically-involved. I'm sure the average Iraqi just wants to have a safe life, but if someone already has a negative view of Americans, that view isn't going to be improved if they lose loved ones to violence. Even if it caused by insurgents, a lot of people I think would blame the Americans anyway - "this wouldn't have happened if Bush hadn't invaded" - and even though things were bad under Saddam, a mangled child in your arms today takes precedence over anyone gassed or shot 10 or 15 years ago.