...This would require a willingness to send American forces back to Iraq. It would mean not merely conducting U.S. air strikes, but also accompanying those strikes with special operators, and perhaps regular U.S. military units, on the ground. This is the only chance we have to persuade Iraq's Sunni Arabs that they have an alternative to joining up with al Qaeda or being at the mercy of government-backed and Iranian-backed death squads, and that we have not thrown in with the Iranians. It is also the only way to regain influence with the Iraqi government and to stabilize the Iraqi Security Forces on terms that would allow us to demand the demobilization of Shi’a militias and to move to limit Iranian influence and to create bargaining chips with Iran to insist on the withdrawal of their forces if and when the situation stabilizes....

Now is not the time to re-litigate either the decision to invade Iraq in 2003 or the decision to withdraw from it in 2011. The crisis is urgent, and it would be useful to focus on a path ahead rather than indulge in recriminations. All paths are now fraught with difficulties, including the path we recommend. But the alternatives of permitting a victory for al Qaeda and/or strengthening Iran would be disastrous.