After liberating Raqqa from the Islamic State of Iraq and Syria (ISIS), the future of Syria remains unclear. The Trump administration heralded the battlefield success of the U.S.-backed forces, and repeated its pledge to suffocate ISIS' expansionist efforts -- yet the head of the Syrian Civil Defense, a Syrian humanitarian group also known as the White Helmets, isn't quite ready to celebrate.

"Not really," Raed Saleh responded in an interview with CBS News, when asked if the Raqqa victory means anything to him. "I'm sure you are surprised," he added.

Saleh has aided victims of the country's incessant violence and fought the human rights abuses of the Assad regime since the civil war began in 2011. He is of the opinion that winning one battle -- even a victory that resulted in the fall of ISIS' self-declared capital -- doesn't guarantee peace and stability.

"When your city is occupied by one terrorist organization and it's liberated or taken over by another organization, and the picture of another terrorist is held up in the city, this doesn't give us any happiness," Saleh said, referring to a photo of the Kurdistan Workers Party (PKK) leader Abdullah Ocalan brandished in Raqqa after it was liberated. Though the PKK is not said to be in control of the city at this time, Saleh warns that instability may come again.

"At least some among the people who entered Raqqa are undisciplined and will cause trouble in the future," Saleh predected when he was in Washington, D.C. last week for a conference on American policy in Syria.

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The civil war, driven by both terrorist groups and the government of President Bashar al Assad, has now left more than 400,000 people dead and driven 11 million people from their homes. Defeating ISIS is at the center of the Trump administration's foreign policy in Syria. The liberation of Raqqa was the most significant accomplishment for the U.S.-based forces in the country in the last year.

"The defeat of ISIS in Raqqa represents a critical breakthrough in our worldwide campaign to defeat ISIS and its wicked ideology," Trump said in a statement released by the White House. "With the liberation of ISIS's capital and the vast majority of its territory, the end of the ISIS caliphate is in sight."

The Trump administration says it has "dramatically accelerated" the fight against ISIS in Syria, mostly through changes in authority that allow the military to act without the impediment of layers of bureaucracy. Nearly 30 percent of the gains in total territory against ISIS by August occurred under the Trump administration, according to a briefing earlier this year by Brett McGurk, the State Department's special envoy for the anti-ISIS coalition.

And the flow of ISIS militants coming out of Syria has been reduced to a trickle. Administration officials point out that ISIS propaganda has stopped encouraging followers to come to Syria to take up the fight. Taking Raqqa away from ISIS has also significantly impacted the messaging from the militant group, given that most of their directives originated from the city, the group's declared capital. MgGurk points out the uphill battle the group now faces in disseminating its messaging from small villages.

ISIS now holds less that 10 percent of the territory it once held, according to the administration, and it is still carrying out attacks. It carried out an attack that cost the lives of four American soldiers in October. Afterward, Joint Chiefs of Staff Chairman Gen. Joseph Dunford told reporters that ISIS would be defeated when the group is no longer able to operate across multiple regions, and when its offshoots in individual countries can be "dealt with by local forces."

But reaching that point, that is, weakening ISIS to the point at which local forces have the ability to curtail ISIS and other terrorist groups in Syria, remains a battle because there are no government forces that can be relied upon for this. Another factor is the U.S. determination that Assad cannot remain in power, a point recently repeated by Secretary of State Rex Tillerson.

"The United States wants a whole and unified Syria with no role for Bashar Assad in the government," Tillerson told reporters last week after a meeting in Geneva about Syria. "The reign of the Assad family is coming to an end, and the only issue is how that should be brought about."

The U.S. maintains support for the Geneva process in Syria, but getting to a place where there is enough peace on the ground to start that process will be a struggle, Saleh said. He doubts the political transition is as close as some in the U.S. government think it may be. Saleh intends to continue his efforts to help Syrians, and hopes that the accumulated efforts might over time result in peace for his country. While he still sees the Assad regime dropping barrel bombs and killing thousands in the country -- and yet, he does not wholly trust the U.S. either.

"We observe human rights violations from all parties and we talk about this when we meet with American and UN officials, but we do end up focusing on the regime's violations," says Saleh. "Not me, no other Syrians nowadays has great hopes on anyone delivering on these big promises, big red lines that we keep hearing (about). The barrel bombs keep dropping, and there is no clear hope."