In November of 2012, Iyas Kadouni, an activist from the town of Saraqeb in northwestern Syria, grew disenchanted with the abuses of some rebel brigades in the area. A few days earlier, a YouTube video had been posted online showing rebels beating and executing captive government soldiers, and Kadouni took to Facebook to condemn it. “We don’t want those who are liberating us from killers to resemble them and take on their values,” he wrote. Soon, he told reporters at the time, he started being bombarded with angry messages from supporters of the rebels, warning him that he was “playing with fire.”

For the next several months, Kadouni stuck it out in Syria, campaigning for the revolution, sharing news with journalists covering it from abroad, and speaking his mind about the course of the conflict. But a rift had formed between him and the leading factions of the rebellion, and by early last summer, Kadouni felt it was time to leave. Some activists he knew had begun to turn the cause into a business enterprise, violating what he considered to be the basic precepts of the revolution and putting people who disapproved in danger. Worse, a sinister new militant organization known as the Islamic State of Iraq and al-Sham, or ISIS, had moved into Saraqeb, displacing the less battle-hardened brigades that Kadouni knew well. “I found myself in a very dangerous situation,” Kadouni told me recently by phone from Brussels, where he now lives.

Over the weekend, President Barack Obama said that he and the intelligence community had “underestimated” the threat posed by ISIS, a group he once dismissed as a “JV team.” The White House has also embarked on a campaign of airstrikes against the group, while pledging to send money and weapons to “moderate” elements of the Free Syrian Army who can help retake ground from ISIS. It’s not yet clear if such moderate factions truly exist; some of the most effective rebel battalions are those with hardline Islamist views, and the preferred FSA units remain undertrained and unreliable. But in the search for the true moderates of the Syrian uprising—the activists and humanitarians who, like Kadouni, eschewed violence and resisted the growing extremism and religiosity of the various rebel brigades—the prognosis is much more clear: The revolution has not had space for them for more than year.

“If you wanted to work for Syria—just for Syria, for the Syrian people—you could not be safe at any time,” Kadouni said of his experience last year. “You would sleep in your house waiting for someone to come kill you.”

It’s a familiar tale for anyone who has observed Syria’s spiraling conflict over the past year and a half, and I was writing about it many long months ago in The Huffington Post. But as American involvement in the conflict rises, so has the potential for wishful illusions about the state of an uprising that has now stretched into its fourth exhausting year. Last month, the Syrian Support Group, a leading organization dedicated to building a moderate opposition, shut down due to inattention and infighting.

The civilian revolutionaries who filled the early days of the uprising with so much promise are today largely spread across the globe, living in Turkey and Lebanon and Europe as refugees or long-distance activists. For some of these original moderates, the end of the revolution came as soon as demonstrators took up arms against a better-armed regime. For many more, the exodus was brought on by the rise of ISIS, in the middle of last year.

Mousab Alhamadee, a highly respected correspondent for the American news service McClatchy, was chased out under threats from ISIS last November. In an essay he published at the time, Alhamadee described how threats from ISIS had driven him from his home. “I have come to realize that activism in an al Qaida-held area not only is deadly, but meaningless,” he concluded.

Late last year, in the city of Gaziantep in southern Turkey, I spoke with a Syrian doctor who told of a similar purge among his own profession in Raqqa. ISIS had recently seized control of the town from an alliance of anti-regime groups, and immediately turned its attention on the revolutionaries and activists who already lived there.

ISIS executed members of other rebel factions, tore down symbols of unapproved religious heritage, and hounded anyone who didn't subscribe to its particular style of living. On more than one occasion, ISIS militants had entered the hospital where the doctor worked and forced him to treat a wounded fighter at gunpoint. At checkpoints, they detained several of his colleagues who were traveling to work—releasing some unharmed, demanding a ransom for others, or worse.

A well-regarded Christian anesthesiologist had recently turned up dead in a part of Raqqa that was controlled by ISIS, the doctor said, an action that made little sense to him given how desperately anesthesiology was needed in rebel-held Syria. “I don’t know why they would do that,” he said, as we walked around town. “They look at the rest of us as non-believers who can be killed or beaten. Like you are nothing.”

Not all revolutionary civil activity has ceased inside Syria. In the town of Kafranbel, in Idlib province, a clever and merry band of activists continue to create humorous banners that comment on recent events, and seek to bring attention to their ongoing plight. (Recent banners have quoted Robin Williams, honored the murdered journalist James Foley, and mocked the world’s obsession with the World Cup.) And in Aleppo, there are revolutionary councils and civilian activists networks, not to mention a noble brigade of volunteer rescuers who risk their lives daily to pull survivors from the rubble of regime airstrikes.

But for so many other would-be do-gooders, the rebel-held countryside, not to mention the major cities still under government control, has long proven unwelcome terrain. Going home remains a distant illusion.

“The sense of despair and the sense of loss is so powerful,” one longtime Syrian activist and humanitarian worker told me by Skype last week from his asylum in London. “For the people still inside, even if they are activists, they are under so much pressure—the pressure of the war, the militarization, the abuse.” He added, “At this point, if you want to be an activist, it’s basically to call for the fighting to stop, the bloodshed to stop.”