Hassan Hassan, co-author of the book ISIS: Inside the Army of Terror, joined Buck to discuss ISIS movements before and since the Syria strikes, as well as the political viability of Assad's displacement.

“What’s going on right now, what’s the enemy doing?” Buck asked to kick things off.

“Raqqa will fall, that campaign will be a success," Hassan said. "The problem is that ISIS has already been building terrain to pull back on. If the United States put that in focus right now, that would be far more effective than allowing them to find another corner.”

Buck talked about something Hassan had written in an excellent piece in the Guardian concerning whether ISIS’s governmental operation has come to a halt.

“They’re trying to retreat to another part of Syria, to the only region that links Iraq and Syria. This is their way of saying they still control both countries. The problem is that the US-led coalition is so focused on Mosul and Raqqa that many ISIS operatives who run the government have started to leave Raqqa and go somewhere else. ISIS is leaving the fighters behind and putting the people who have been in charge of running the caliphate elsewhere.”

“Like the Taliban moving from Afghanistan into Pakistan again,” observed Buck.

“Exactly," said Hassan. "They’re looking to rebuild the third capital of ISIS, aside from Mosul and Raqqa, in the areas in Syria where Iraq and Syria meet. ISIS is not hiding that—they’ve been talking about it since last year.”

Buck asked about the condition of anti-Assad forces that are not ISIS, inquiring as to what territory are they holding.

“This is the biggest challenge going forward,” said Hassan. “They are not doing well. They’re divided into two blocks mainly. One works mainly with Turkey, and Turkey is using them as a potential proxy against the Kurds in the North. Turkey claims to have liberated 5000 square kilometers using that army in that region.”

“Elsewhere rebels are concentrated in the West and South. They’ve lost Aleppo, have been on retreat in Damascus, and have not been doing very well. More importantly, they are losing the support of regional backers.”

Buck asked for a realistic scenario involving the removal of Assad.

"I don’t think it’s a realistic scenario," said Hassan. "Turkey, Iraq, and other major powers in the region do not want Assad to fall abruptly, because if that happens, they don’t know who is going to take over.” 

"The problem is a political settlement is not going to happen unless the United States is ready to say enough is enough from Assad, and to act on that."

Click on the media above to hear the interview in full.