A mortar blast shook the rooftop where Hunter Pugh stood watch over the last stretch of Syria controlled by the Islamic State, and he scanned the winter dawn, trying to decide whether it had been outgoing fire or an attack zeroing in on his post. The answer came from a second mortar round hitting even closer. Then a third and fourth.
But before he could scramble for cover, a missile from an unseen American fighter jet shot over his head and slammed into a distant courtyard, reducing the ISIS mortar team to an exclamation point of dust and smoke. Once again, the might of the American-led military coalition had come to his rescue.
Mr. Pugh is not an American soldier. He is a 25-year-old cook from Pennsylvania who traded his spatula for a Kalashnikov eight months ago and went to Syria to fight ISIS as a volunteer for a Kurdish militia, as hundreds of civilians from Western nations have done in recent years.
Through the grinding battle to reclaim northeastern Syria from militant control, the volunteers and the militias they joined have received crucial protection and support from the United States military. But the Trump administration is now considering a swift withdrawal from Syria — and American volunteers like Mr. Pugh are worried about where that will leave them.
“The coalition pretty much has our backs — they are really the dominating force here,” Mr. Pugh said in a telephone interview, with sporadic machine-gun fire and explosions audible in the background. “It’s anyone’s guess what happens when the U.S. pulls out.”
With ISIS-held territory reduced to a few villages, the tangled conflict in northeastern Syria is moving toward a new and uncertain phase. Experts say that Turkish forces hostile to the Kurds, no longer restrained by an American presence, could sweep in from the north. Syrian government troops backed by Russia and Iran might drive from the west. Rival anti-ISIS militias could squabble or shift allegiances. And the scattering of American volunteers could be caught in the middle.
“You could potentially have one ally firing on another,” said Amanda Sloat, a senior fellow at the Brookings Institution and a former State Department official who specialized in the region. “The U.S. pulling out creates a huge potential for chaos.”
Of the Western civilians who have gone to Syria as volunteers over the years, a radicalized few joined ISIS or other militant groups. But many others went to fight against ISIS — most often by joining one of the United States’ most reliable allies in the region, the Kurdish People’s Protection Units, known as the Y.P.G. Mr. Pugh’s squad on the rooftop that morning included a welder from Arizona, a steelworker from Canada and a motorcycle mechanic from Texas.
Mr. Pugh and other American volunteers estimate that about 30 foreigners are now embedded with the Y.P.G., the dominant group in the Syrian Democratic Forces alliance fighting ISIS. (The militia did not respond to requests for an official count.)
Some are military veterans looking to settle unfinished scores; others are an eccentric breed of war tourist seeking a thrill. Still others are left-leaning idealists attracted by the Kurds’ talk of creating a socialist democracy called Rojava, with workers’ cooperatives and a constitution that recognizes environmental sustainability, religious freedom and gender equality.
“I’ve always hated capitalism and materialism,” said Warren Stoddard, a 24-year-old from San Marcos, Tex., who joined the same infantry squad as Mr. Pugh. “What the Kurds are doing fits with what I believe.”
Mr. Stoddard graduated from college in 2018 with a degree in creative writing and the cover illustration from Ernest Hemingway’s novel “The Sun Also Rises” tattooed on his forearm. He said he weighed two options for what to do next: a cross-country motorcycle trip, or taking up arms in Syria.
“The situation with the Kurds looked like Poland, 1939,” he said in a telephone interview. “I thought they could use my help.”
The United States has been trying to deter its citizens from engaging in this sort of freelance warfare since the nation’s earliest days: President Washington issued a Proclamation of Neutrality in 1793 warning Americans not to get involved in the French Revolution. But a steady stream of idealists, romantics, opportunists, mercenaries and filibusters have jumped into foreign frays anyway — riding with Pancho Villa in Mexico, fighting fascists in Spain, ferrying arms to Cuba, battling communists in Africa and even trying to establish new slave states in Central America.
Those adventures often ended badly — sometimes in front of a firing squad. Thomas Paine, the author of “Common Sense,” spent a year in a dank cell in revolutionary Paris. Western leftists who went to fight in the Spanish Civil War, like the British writer George Orwell, had to flee when communist allies turned on each other. More recently, John Walker Lindh, an American who joined the Taliban before the terrorist attacks of Sept. 11, 2001, was captured in Afghanistan, prosecuted in the United States and sentenced to 20 years in prison.
Senior American military officials, including Special Operations troops who have served in Syria, said they viewed the American volunteers there as somewhere between a curiosity and a nuisance on the battlefield.
Nearly a dozen Americans who joined the Kurdish militia have died in Syria, according to a website maintained by the Y.P.G.
Others have returned to the United States, where they are often detained on arrival for questioning about their activities. So far, none have been prosecuted. But that could change if Turkey — a NATO ally — goes to war with the Kurdish forces in Syria.
Federal prosecutors evaluate each case of a returning American militia volunteer “to determine whether a violation of our laws occurred,” said Marc Raimondi, a Justice Department spokesman.
But he warned: “Regardless of the legality, it is a really bad idea for Americans to join such groups.”
In a statement, the State Department cited its travel advisories and said: “The U.S. government particularly warns private U.S. citizens against traveling to Syria to engage in armed conflict.”
Mr. Pugh, like many before him, said he left home because he felt trapped in a dead-end job and wanted to live a life of meaning. He got the idea of volunteering with the Kurds from an article in Rolling Stone, and contacted the Y.P.G. through the group’s recruiting website. He said he was sent encrypted email instructions to fly to Iraq, where he would be met. So in May 2018, he bought a one-way ticket and took with him only a small bag of clothes and the complete works of Ernest Hemingway.
Both Mr. Pugh and Mr. Stoddard said that on arrival, they went through weeks of language classes, military drilling and “ideology training” about the history and political beliefs of their Kurdish hosts.
Mr. Pugh said he soon came to love the Kurdish people’s generosity and their talk of building an egalitarian society, with features like having most leadership positions shared by a man and woman.
By January, the volunteers said, they were embedded with a mixture of Kurdish fighters and their Arab allies in a burned-out village on the front, peering through small “kill holes” that offered a protected view of ISIS-held territory.
Their mission took on a steady rhythm: Set up defensive gun positions by day, push forward by night, squeezing the militants house by house.
As the militia squads advanced, Mr. Stoddard said, they would sometimes encounter American Special Operations troops who were working closely with the Kurds, but the American troops were careful to steer clear of volunteers like him.
“They are friendly, they’ll say ‘Hi,’” he said. “But they don’t want to get mixed up with us. They think we’re crazy to be here.”
Ahead of the militia would march the thunder of coalition airstrikes. In just four weeks in January, the coalition conducted more than 1,200 strikes in Syria.
“It was all the time, so much that you almost felt bad for ISIS,” Mr. Stoddard said. “Sometimes it would come in danger-close, and then it feels like the whole world is ending and the sky is ripping open.”
ISIS was only able to counterattack, he said, when dust storms or fog hid its fighters from easy detection by American drones and aircraft.
On one of those dusty days, Mr. Pugh said, he was peering down his rifle when a large-caliber bullet punched through the wall just above his head, peppering his face with grit. He took cover, and then a call came over the radio: More fire had pierced a wall near Mr. Stoddard, hitting his thigh and foot and barely missing his head. He was bleeding badly.
Mr. Stoddard said that an Arab fighter hefted him over his shoulder and ran through mortar fire to a truck that whisked him to a field hospital staffed by American troops — another vital asset to the local forces that could disappear if the United States pulls out of Syria.
Mr. Stoddard said he spent four days in the field hospital, and two weeks later flew back to the United States, where he is recovering from his injuries in Alabama.
Mr. Pugh is still in the fight. Speaking on Tuesday from a bombed-out building where he had managed to find spotty cellphone service, he said that ISIS was still putting up fierce resistance, and had fired several rockets at the building his squad was holding.
With ISIS down to its last few square kilometers, Mr. Pugh said the fight for its territory would probably soon be over — and then, “I’m wondering what my use and place will be.”
Maybe he would return home and go back to school, he said. Maybe he would try to enlist in the United States military.
But if his Kurdish friends were threatened by Turkey or anyone else, he said, he would probably stay and fight, even if it meant turning weapons on an American ally: “It’s far better to shed blood in an act I absolutely believe in.”