Is anyone winning the war in Syria? For the past month, there's been a stream of reports that the regime of President Bashar al-Assad has been weakening, that Assad's foreign support is softening, that members of his regime are arranging for visas, thinking about a hasty exit, that Assad's army is tolerating advances by ISIS, perhaps to frame the conflict as one between his regime and the still more brutal alternative. For a reality check on these various claims, we turn now to Lina Khatib. She runs the Carnegie Middle East Center and is in London today.

Welcome to the program.

LINA KHATIB: Hello, thank you.

SIEGEL: And first, is the Assad regime significantly closer to collapse today than it was, say, a year or two ago?

KHATIB: I wouldn't say it's close to collapse, but it has definitely been weakened in the battlefields. The regime has lost many of its troops. The army is now down to just 40,000. And it's become more and more reliant on external support from groups like the Lebanese militia, Hezbollah, as well as Iranian troops on the ground.

SIEGEL: What do you make of one of the most puzzling reports out of the war, which is that the Syrian army did nothing to block recent gains by ISIS, perhaps not only tolerated but might have welcomed their gains. Is that something intentional or a measure of the weakness of Damascus?

KHATIB: There has been a tactical indirect cooperation between the regime and ISIS in the sense that when Assad finds that ISIS can advance into an area that has significant presence for the moderates here in opposition, the regime is not standing in the way of ISIS because. Because of the weakness of the regime itself on the ground, it is seeing in ISIS a useful tool in order to try to eradicate the moderate opposition.

SIEGEL: You're saying the reasoning there would be that Assad would benefit by having more unpalatable enemies on the battlefield, and that would be the case if ISIS were stronger than the Free Syrian Army.

KHATIB: If ISIS became the only force in this conflict, if the moderate opposition is eradicated, then Assad can then appeal to the international community to say that it's either his regime or these extremist Islamists who have no allies anywhere else in the world.

SIEGEL: Another Islamist group fighting against Assad is the Nusra Front, which is - we say is allied with al-Qaida. What does that mean that this group is allied with al-Qaida?

KHATIB: Nusra is the Syrian franchise for al-Qaida. But Nusra is also very much a Syrian product. Most of its members have joined Nusra not because of ideology, but because Nusra has proven itself to be one of the few groups on the ground that have been consistently fighting the regime from the very beginning.

SIEGEL: But it takes orders from Ayman al-Zawahiri, the head of al-Qaida?

KHATIB: Actually, Nusra does not take orders from Ayman al-Zawahiri. It uses Ayman al-Zawahiri as a religious reference point and it uses the affiliation with al-Qaida for the sake of legitimacy as well as to get donor money from those al-Qaida sympathizers around the world. But in terms of its operations, it is very much a local organization that is actually rather sensitive to the nuances of operating in this Syrian environment, and that has been a key reason why it has been successful on the ground because the population does not see it as a foreign entity the way the population looks at ISIS, for example.

SIEGEL: Lina Khatib, it sounds, from the way you describe the state of things in Syria, that this war that's been going on for more than four years could go on for another couple of years and no victory or resolution seems especially near at this point. Am I reading you right?

KHATIB: We are very far from seeing any victory. The forces fighting on the ground are all just about able to hold their heads above water. The regime is not about to collapse, but it's not going to win. ISIS also will find it very difficult to take over all of Syria and the moderate opposition in the South is making more progress, but again, not enough to be able to end this war. And the same would even apply to Jabhat al-Nusra.

But we are beginning to see a shift in the trajectory of the conflict towards more weakening for the regime. The turning point, I think, will happen when regional powers, mainly Iran, Saudi Arabia, Turkey and Qatar, engage in dialogue about what should happen in Syria because they can then push the situation on the ground in a particular direction, hopefully that of a transition. But to reach this stage of negotiations takes a very long time. And first we have, of course, the hurdle of the nuclear negotiations with Iran and also to come up with a strategy for the transition, which is currently not present. So we are definitely talking about a long process still.

SIEGEL: Lina Khatib of the Carnegie Middle East Center, thanks for talking with us today.

KHATIB: Thank you.

This interview was originally broadcast by NPR All Things Considered.