Was this victory all I wanted? No. I wanted a garrison of troops for stability. We've kept troops in Germany for longer than anyone I've debated Iraq with has been alive and that's served us well. I didn't like the continuing level of domestic terrorism in Iraq, but we didn't go in to stop attacks on Iraqis and the murder rate in Chicago is also high without it being grounds for calling the war a loss. The new Iraqi government was doing reasonably well for the third world. It could pass a budget (unlike the USA). So I'd been thinking we had a victory, but not a total victory.
What's making me admit defeat isn't just that ISIS (expelled from Al Qaeda for brutality--"that must have taken some doing") is capturing cities in Iraq. It's that the Iraqi Army is deserting in combat by the thousands and the parliament can't even come together to deal with the emergency. Which says to me that the corruption has eaten out the state to where it can't stand.
Partitioning Iraq is bad because of the potential domino effect in redrawing the map. But if the western section of Iraq became a Sunni state ruled by corrupt tribal leaders I'd think we'd still eked out a marginal victory. Having that area ruled by an aspiring Caliphate ready to send out terrorists and jihadis to conquer the whole world is the worst case, an unmistakable defeat.
I can think of several explanations for how we got here from what looked like victory a few years ago:
1. Lack of follow-through. US troops would have discouraged the corruption and ethnic discrimination in the Iraqi Army and kept it more coherent (training & maintenance). US back-up would have held up their morale so they didn't break and run. For example, the troops in Mosul would've had air support and assurance that a US-led counter-attack would deal with any ISIS breakthroughs.
2. Great Man Theory. Iraq needed a hero along the lines of Washington, Joan of Arc, or Ataturk to weld it into a solid nation. No one stood up. Possibly because Saddam had put all the potential candidates through shredders. But that makes a nation-building project doomed, or at least a high-risk gamble.
3. Culture is King of All. Arabs can't do democracy because they'll always choose the welfare of their clan and sloth over the success of the nation. If so, the future looks grim.
Where do we go from here? The key issue is that the American people aren't willing to take the offensive in the Middle East any time soon. The current leadership probably can't pull one off anyway. A Libya-type attack wouldn't improve the situation for very long. Partition Iraq? Ally with Iran to enforce Shiite control over Iraq? Pull out and let them slaughter each other? The last is tempting after watching the current mess but I'd want to give the Kurds some support, they always stood by us and we don't have enough good friends to get away with betraying the ones who do like us. Besides, we'll be back eventually and we'll need bases.
The problem with letting the Middle East sink into the swamp is eventually they'll hit a lull in the mutual slaughter and start spawning alligators again. The last time some bright boys inspired by the Death-To-America mobs got a nifty idea, we lost over 3000 people. Moore's Law is cranking away so the next time we can expect a zero or two to be added to the death toll. I don't see any way to take away their motive for attacking. We're still using man-made law instead of obeying Sharia, and we're going to keep doing that.
So what do we do then? Launch a pure punitive expedition and just trash the country enough to discourage everyone from doing it again? That just restarts the cycle. Pick another Arab country to make a democracy of and try for better follow through? Nice plan, if we can actually muster the willpower for follow-through. Probably not an option when 40+% of the population is caring more about domestic politics than the war they're in. Miracle? I'd take one.
A repeating cycle of terror attack and punitive expedition would reach its endpoint in a few loops. Either the terrorists would find a way to destroy our country--or they'd manage to piss us off badly enough to unleash genocide. In the state diagram of the war I did a while back, this would be the "Graveyard World" or "Arabia Delenda Est" outcomes. I don't like either of those, even if I do have a strong preference between the two (We've currently moved back to "Acceptable Level of Violence").
* Subject line is from a bit of advice apocryphally given to Alexander the Great.