AL HAWL CAMP, Syria — She was a 20-year-old college student in Alabama who had become convinced of the righteousness of the Islamic State. So she duped her parents into thinking she was going on a college trip, and instead bought a plane ticket to Turkey with her tuition money.
After being smuggled into the caliphate, the student, Hoda Muthana, posted a photograph on Twitter showing her gloved hands holding her American passport. “Bonfire soon,” she promised.
That was more than four years ago. Now, after being married to three Islamic State fighters and witnessing executions like those she had once cheered on social media, Ms. Muthana says she is deeply sorry and wants to return home to the United States.
She surrendered last month to the coalition forces fighting ISIS, and now spends her days as a detainee in a refugee camp in northeastern Syria. She is joined there by another woman, Kimberly Gwen Polman, 46, who had studied legal administration in Canada before joining the caliphate and who possesses dual United States and Canadian citizenship.
Both women, interviewed by The New York Times at the camp, said they were trying to figure out how to have their passports reissued, and how to win the sympathy of the two nations they scorned.
“I don’t have words for how much regret I have,” said Ms. Polman, who was born into a Reformed Mennonite community in Hamilton, Ontario, to an American mother and Canadian father and who has three adult children.
Ms. Muthana, who attended high school in Hoover, Ala., and the University of Alabama at Birmingham, said she was first drawn to ISIS in high school reading Twitter and other social media posts.
“Once I look back on it, I can’t stress how much of a crazy idea it was,” she said. “I can’t believe it. I ruined my life. I ruined my future.”
In a tweet this weekend, President Trump criticized allies including Britain, France and Germany for not taking back hundreds of ISIS prisoners captured on the battlefield. “The alternative is not a good one in that we will be forced to release them,” he warned.
The president made no mention of American women who had married ISIS fighters and whom the United States had not returned home. Both Ms. Muthana and Ms. Polman said they had not been visited by American officials since their capture last month. They also said there was a family of four sisters from Seattle, with four children, who were being detained in a separate camp. A former law enforcement official confirmed that a Seattle family had traveled to Syria to join the Islamic State, but did not have further information.
A small number of Americans — as few as 59, according to data tracked by the George Washington University Program on Extremism — are known to have traveled to Syria to join ISIS. Nearly all the American men captured in battle have been repatriated, but it is unclear why some of the American women and their children — at least 13 known to The Times — have not been.
A spokeswoman for the Federal Bureau of Investigation declined to comment on the two cases, but said that agents would typically work to build a criminal case against any American who joined the Islamic State, a designated terrorist organization.
Robert Palladino, a spokesman for the State Department, on Tuesday described the situation for Americans in Syria as “extremely complicated.” He said, “We’re looking into these cases to better understand the details,” but declined to comment further, citing privacy and security concerns.
A Canadian government official said that it could be difficult for Canadians detained in Syria to leave the region because they were likely to face serious charges in neighboring countries.
Citing the many crimes committed by ISIS, Seamus Hughes, deputy director of the George Washington program, said there were “thousands of legitimate reasons to question the sincerity” of appeals like those of Ms. Muthana and Ms. Polman.
“The foreign women of the Islamic State, while often reduced to simplistic narratives about ‘jihadi brides,’ ‘brainwashing’ and ‘online grooming,’ aided and abetted many of these atrocities and in some cases directly perpetrated them,” he said.
Ms. Muthana and Ms. Polman acknowledged in the interview here that many Americans would question whether they deserved to be brought back home after joining one of the world’s deadliest terrorist groups.
“How do you go from burning a passport to crying yourself to sleep because you have so much deep regret? How do you do that?” Ms. Polman asked. “How do you show people that?”
The daughter of Yemeni immigrants, Ms. Muthana grew up in an ultra-strict household — no partying, no boyfriends and no cellphone.
When she finished high school, her father gave her a phone as a graduation gift. It soon became her portal to the world of extreme Islam, she said.
Two years later, in 2014, an online contact walked her through the steps of joining the Islamic State, she said: Board a flight to Turkey. When you land, call this number.
To pay for the trip, Ms. Muthana enrolled in classes at the University of Alabama at Birmingham, where she was a sophomore business major, but then withdrew and cashed the tuition check from her parents. She packed a book bag with her clothes and told her family she was going to an event in Atlanta, a two-hour drive away. Instead she headed directly to the Birmingham airport for a flight to Istanbul.