Basically, that beating the Islamic State, which has become the vanguard of a Sunni insurgency against the Baghdad government, needs a political not a military solution.
Of course, you hear of neither from the Shiite-dominated government, which is relying on ad hoc sectarian militias, some beholden to Iran, to roust the Islamic State from Sunni towns in central and western Iraq. These militias are proving once again to be terror gangs, making reconciliation with the Sunnis all but impossible.
Petraeus was commander of the 2007 “surge” of US forces in Iraq, which with Sunni tribal help, was able to subdue an al-Qaeda linked insurgent grouping. Even before then, he was an advocate of incorporating Sunnis into Iraqi political life and to integrate them into the army and security services. Failure to do that–along with Bush and Obama Administration inattention to that problem, laid the groundwork for the new and vigorous rebellion.
Here are Petraeus’ comments to the BBC.
Human Rights Watch reported on militia atrocities back in March,