 -- As the Obama administration debates expanding its air offensive against the Islamic State of Iraq and Syria (ISIS) from Iraqi Kurdistan into eastern Syria, its main challenge remains finding a reliable military partner on the ground. We asked Douglas Ollivant, a senior national security studies fellow at the New America Foundation who focuses on Iraq, to weigh in on how lessons from that arena could shape the battle on Syrian terrain.

Syria Deeply: What's the main challenge facing the U.S. in finding a partner on the ground in Syria?

Ollivant: The people who make sense militarily make no sense politically, and vice versa. And that's a real problem. The Free Syrian Army (FSA) is fighting for its life, and no matter how much training and equipment we give them, they're not going to be able to take the fight to ISIS in a serious way, even with U.S. air power behind them. Switching horses mid-stream to back the Assad regime makes the most military sense, but isn't politically possible. Besides ISIS's taking of their air force bases in Raqqa, the regime has actually had some decent success against ISIS.

Militarily, all that's going on is that the U.S. is keeping ISIS from expanding in Iraq and certainly from expanding in Syria. It's keeping ISIS from expanding in Iraq until the new Iraqi government forms and the U.S. has a reasonably reliable partner on the ground. There's a deadline – they only had 30 days from the date that Abadi was named prime minister.

Syria Deeply: If the new Iraqi government does not form, is the U.S. left without a reliable partner on the ground?

Ollivant: That's certainly a possibility. If they don't form a government, then Maliki stays on as the acting prime minister, and no one wants that. So there's a kind of forcing function here, in that Maliki stays if the Iraqis don't find somebody else. That's going to make it very complicated for the U.S. to find a unified, reliable partner on the ground. What the U.S. is looking for is someone who can get all of the unified factions in Iraq working together on the ground in a way the U.S. Air Force can then support from above.

Predator Drone Reportedly Spotted Over ISIS Stronghold

ISIS Strategy a Moving Target for Obama Administration

Obama Says US Will 'Degrade and Ultimately Defeat' ISIS Like Al Qaeda

Syria Deeply: Do you ever see a situation where the U.S., unable to find a suitable partner on the ground, goes in alone?

Ollivant: It won't. It's just not politically possible, not in the American political arena or in the region: no one there would accept a U.S. ground invasion of Syria. You can attack from the air but without a ground force, air power will be limited. What the U.S. would like is something like what happened in 2011 in Libya – have a decent ground force that you can support with air power. But in Syria, it's hard. It would be lovely if we could reach a negotiated settlement [with the Assad regime] and get [it working with the U.S.] in parallel, if not in tandem.

Syria Deeply: Could the Kurds be that partner?

Ollivant: It could be the Kurds in the north, they're possible and they do have a live fighting front with ISIS. The question is: are the Kurds interested in pushing south against ISIS? Are they interested in pushing into non-Kurdish areas? The other piece that's getting really interesting is that the group that played the largest part in rescuing the Yezidi in northern Iraq last month was the PKK. So it's really a reshuffling of allies there.

This article originally appeared on Syria Deeply.