Yes Al Queda terrorist did do this. Can you see what is happening? They are trying to do what Bin Laden said he would do. To make it a holly war. Brother against brother or radical beliefs vs non radical.
Each one of those countries favors each one of the three differ types of people living there. I am not sure who likes the Kurds or backs the, but seems to me that Iran backs one and Saudia Arabia backs another. Everyone is jocking for control. This is sad to say but probably true.
In the long run, see what destruction it could be if it turns out to be a religious war crossing all the middle east and even around all the world?
This is a short read but tells alot why and about this civil war.
http://atheism.about.com/library/FAQ..._IraqIndex.htm
It is more than religion as you can see one was treated worse than the other when Sadam was in power and the other is fighting back now. It is also religion playing a part. See why Syria, Iran, Iraq, Lebanon, Jordan, Saudia Arabia and all the middle east needs to be in harmony? A Sunni, Shia and a Kurd should all be equal and treated good by each mother and all. If differ countries keep backing differ groups and then you throw Al Queda in and all they care is havoc and destruction, see what happens?
You need these other countries around Iraq to help all in all this. Not for them to back a certain people or group with money, weapons and etc. I feel it is a hard thing to stop.