The deal reached yesterday by the Iraqi cabinet on revenue-sharing of the country’s vast oil reserves could very well be a key turning point in Iraq’s road to stability. It still has plenty of hurdles to overcome — to become law, it has to be enacted by the legislature; to become effective, corruption in the Oil Ministry will have to be addressed and foreign investors will have to be convinced that contracts will be honored and security can be ensured. But this is an enormous step in the right direction. Ambassador Zalmay Khalilzad deserves high praise for his perseverance.

An elemental objection of many of us democracy-project skeptics has been whether the Iraqis really view themselves as a single country with a common destiny. The jury is still very much out on that, but a path to success is clear: the three major factions have to come together not to sing kumbaya but to solve difficult national challenges jointly.

The Iraqis have two such challenges in their immediate future: the security situation and laying the groundwork for a functioning economy in which Iraqis perceive it is more in their interest to be together than to go their separate ways. Longer-term challenges will involve the role of Islam in Iraqi life and the nature of relations with Iran. None of this is easy, but none of it is hopeless — far from it, and it is entirely possible that success in overcoming the immediate problems would foster a unity that would clear the path to reasonable, joint solutions on other challenges. That kind of unity, tested by fire, is the kind of foundation real democracy might be built on.

Victory here is by no means assured, and there is still great cause for concern that we are not sufficiently focused on how to win the wider war against jihadists. But a way for the U.S. to win in Iraq is taking shape. It’s visible. It will require patience and resolve. Which is a long-winded way of saying: It is utterly irresponsible at this critical moment to be doing anything other than supporting the mission — no matter how you feel about whether we ought to be in Iraq in the first place, and no matter what you think about the way things have been handled up until now.