“It has nowhere near the roots, the numbers and the structure that al Qaeda in Iraq and the associated Sunni insurgents had when we launched the surge,” he told a crowd in Denver last night. Okay, but … we have nowhere near the roots and resources that we had in Iraq when we launched the surge either. Here’s a question I keep thinking about: Who’s going to do the street-to-street fighting once we’ve frozen ISIS’s advance with bombing and they start to hunker down in the cities they control? Are the Iraqi army and the peshmerga prepared to kick down thousands of doors in Iraq, city after city? Even if they are, who’s going to do it in Syria, where ISIS is based?

Not the “moderate” rebels, right? Please tell me it’s not the “moderate” rebels.

After more than three years of civil war, there are hundreds of militias fighting President Bashar al-Assad — and one another. Among them, even the more secular forces have turned to Islamists for support and weapons over the years, and the remaining moderate rebels often fight alongside extremists like the Nusra Front, Al Qaeda’s affiliate in Syria…

Most have no effective links to the exile Syrian National Coalition, meaning they have no political body to represent their cause. And the coalition’s Supreme Military Council, which was intended to unite the moderate rebel forces, has all but collapsed…

The approach — training and arming local fighters — has also not been effective in other arenas, whether Iraq, where the military melted away when ISIS attacked, or in Mali, where forces trained in counterterrorism switched sides to join Islamist fighters.

One rebel commander told the Times it’s stupid to think Sunni rebel factions will spend much time fighting ISIS. Why would they? They’re focused on the common enemy, Assad. So imagine a scenario where we build up the “moderates,” they end up joining forces with ISIS in overrunning Damascus, and then ISIS overpowers them in the ensuing battle for control of Syria. What a “mission accomplished” moment that would be.

I spitballed last night that maybe this idea about training Syrians to fight ISIS is actually just a ploy by which troops from other Sunni countries in the region, e.g., Saudi Arabia and Jordan, will have a pretext to enter Syria posing as locals. Read this story, though, and tell me whether it sounds like our “allies” will be willing to make that sort of sacrifice.

Many Arab governments grumbled quietly in 2011 as the United States left Iraq, fearful it might fall deeper into chaos or Iranian influence. Now, the United States is back and getting a less than enthusiastic welcome, with leading allies like Egypt, Jordan and Turkey all finding ways on Thursday to avoid specific commitments to President Obama’s expanded military campaign against Sunni extremists…

While Arab nations allied with the United States vowed on Thursday to “do their share” to fight ISIS and issued a joint communiqué supporting a broad strategy, the underlying tone was one of reluctance. The government perhaps most eager to join a coalition against ISIS was that of Syria, which Mr. Obama had already ruled out as a partner for what he described as terrorizing its citizens.

Some Arab leaders appeared to fear a domestic backlash, perhaps like the attacks against Saudi Arabia by Osama bin Laden and others after the kingdom allowed American troops to use its territory as a staging ground during the Persian Gulf war in 1991. Also looming was a broader worry that airstrikes could increase soft support for, or reluctant tolerance of, the group.

We’ll be doing the heavy lifting, as usual, even though it’s the local Sunni monarchies with which we’re allied that have the biggest stake in defeating ISIS. See now why military experts keep warning that a bigger force of U.S. ground troops is all but inevitable?

But even if it is, it’s not Americans who are going to be fighting street to street in ISIS’s Syrian capital, Raqqa. That’s so far afield politically from what Obama promised on Wednesday night, it’s hard to believe voters would ever tolerate the casualties. It’s also hard to believe any “moderate” rebel force will be strong enough within the next, say, five years to do that fighting for us. If anyone’s going to do it, it’s going to be — ta da — Assad’s troops, with Iranian backing. Right? And that assumes that Assad will have the means and motive for reconquering cities in Syria now held by ISIS. If the U.S. can hem ISIS in to a few strongholds like Raqqa, maybe Assad will be content to leave them alone there while he re-consolidates power in the rest of the country. Why, we might even end up with U.S. and Syrian air assets bombing Raqqa in tandem informally. Either way, to truly “destroy” ISIS, there’s bound to be some sort of quiet coordination with Assad at some point.

For what it’s worth, contra Petraeus, an unnamed U.S. general told WaPo the other day that defeating ISIS would be much harder than anything we’ve done in Afghanistan or Iraq. Gulp. Exit question: Does Assad want to destroy ISIS? Having them around is useful to him as a way to keep the west preoccupied.