The first thing they need to do is Secure the Iraq border. Apparently terrorist agents are crossing from Saudi Arabia to Iraq. They are killing civilians to foment a civil war.

It's not practical to build any kind of fence or wall. But maybe officially sealing off the borders in Iraq, and patrolling the areas with cameras and an alert system will help.

I think most of the violence stems from these foreign Terrorists who commit violence in the guise of being Iraqis. The secondary violence comes from reprisal attacks from Iraqis who are fed up (but they usually just attack members of the group they thought attacked them).