How 'bout we close off Sadr City again? That cut down the sectarian violence to practically nil while it lasted. It worked beautifully.
Then again, the French tried that in Algiers, and it didn't work out too well long term. Plus the Iraqi president's a wuss and already nixed it once.
This war really is like Vietnam. Every time you try something that works, it gets taken away for political reasons. Sigh................