A 34-year-old man from Houston who is said to have sent a résumé and cover letter seeking a job with the Islamic State has been seized on a battlefield in Syria, an American-backed militia fighting the militants said Sunday.
“Dear Director, I am looking to get a position teaching English to students in the Islamic State,” the Texan, Warren Christopher Clark, is said to have written in a letter found in an Iraqi house once occupied by the militants.
Mr. Clark once worked as a substitute teacher in the Fort Bend Independent School District in Sugar Land, Tex., according to his father, and seemed prepared to draw on that experience.
“I believe that a successful teacher can understand a student’s strengths and weaknesses,” he wrote, “and is able to use that understanding to help students build on their understanding of the English language.”
A University of Houston graduate, Mr. Clark moved to Saudi Arabia to teach English and then taught English for three months in Turkey, according to documents recovered in a house in Mosul, Iraq.
Mr. Clark’s résumé ends in June 2015, indicating that he probably joined the Islamic State after that.
His father, Warren Clark, 69, described his son as “a humanitarian” and rejected any suggestion that he would throw in his lot with a group like ISIS. “My son would not be involved in anything along those lines,” he said.
Mr. Clark said he had learned of his son’s letter to the terrorist group “on the news, basically,” and declared,“My son doesn’t have an evil thought in his mind about hurting anyone.”
The militia that announced Mr. Clark’s capture, the Syrian Democratic Forces, said he had been seized along with a man they described as another American, Zaid Abed al-Hamid. The militia said it had also detained other foreign fighters, including citizens of Ireland and Pakistan.
The men were taken during an operation targeting the Islamic State’s last pocket of control in northern Syria, according to a statement issued by the Syrian Democratic Forces, the Kurdish-led and American-supported militia that is fighting to take back territory from the militants.
Only four other Americans are known to have been captured on the battlefield in Iraq and Syria, according to a database maintained by George Washington University’s Program on Extremism. Very few Americans have returned to the United States after joining the terrorist group.
If Mr. Clark and Mr. Hamid, whose surname was also spelled al-Hamed, are extradited to the United States, they would be only the 15th and 16th American adults to return from joining ISIS in Iraq and Syria.
“The number is minuscule,” said Seamus Hughes, the deputy director of the program at George Washington. “To put it in context, the Brits are talking about hundreds of returnees.”
Mr. Clark’s letter and accompanying résumé, which were authenticated by Mr. Hughes, point to his naïveté and suggest that he was drawn to the Islamic State’s promise of building a Muslim-only state.
Little is known about the American said to be captured alongside Mr. Clark, beyond his age, 35. The Syrian Democratic Forces did not say what state he is from, describing him only as “originally from the United States.”
There were indications, however, that Mr. Hamid might not really be American.
His name appears in a database of 130 Trinidadians who joined the Islamic State that is maintained by Simon Cottee, a senior lecturer in criminology at the University of Kent who tracks the group. Mr. Cottee is working on a book about ISIS fighters from the Caribbean nation.
Mr. Hamid has been identified as an extremist since at least 2011, when he was detained in Trinidad as part of an alleged plot to kill the country’s prime minister.
According to Mr. Cottee’s database, Mr. Hamid joined the terrorist group on April 6, 2014, along with his wife and his three children. A much plumper Mr. Hamid appears in an ISIS video, sitting by a languid stream, railing about how his family could not practice their faith in Trinidad.
Mr. Cottee said that he had shared the mug shot published by the Kurdish militia with people who knew Mr. Hamid in Trinidad, that they had confirmed his identity.
Still, Mr. Cottee did not rule out that the possibility that Mr. Hamid is a dual citizen.
A similarly spelled name — Zaid Abdul-Hamid — appears in a cache of ISIS registration forms indicating that he provided a reference for a recruit from Trinidad and Tobago when that recruit joined the group in 2014. The form indicates that Mr. Abdul-Hamid was in Raqqa, Syria, at that time.
Col. Scott Rawlinson, a spokesman for the American-led military coalition in Baghdad, said in an email that the coalition was “aware of open-source reports of reportedly American citizens currently in custody believed to be fighting for ISIS.”
“However, we are unable to confirm this information at this time,” he said. “The incident is under investigation.”
Last month, President Trump’s announcement that the United States would withdraw forces stationed in Syria prompted the resignation of his defense secretary and accelerated the resignation of the White House’s senior envoy to the fight against the Islamic State. Both Defense Secretary Jim Mattis and the envoy, Brett McGurk, said that the unexpected withdrawal amounted to abandoning America’s allies in the region, especially the Syrian Democratic Forces.
In recent days, White House officials have softened Mr. Trump’s stance, saying that the withdrawal will not happen right away and that it will be carried out in a coordinated manner. On Sunday, the president’s national security adviser, John R. Bolton, appeared to reverse course, telling reporters in Jerusalem that the pullout was conditional on defeating the last remnants of ISIS and on Turkey’s ensuring the safety of America’s Kurdish allies.
According to three separate reports, including an assessment by the Pentagon’s inspector general, the Islamic State still maintains a force of 20,000 to 30,000 members in Iraq and Syria.
The last time the group was declared defeated was in 2010, when the C.I.A. estimated that it was down to just 700 fighters.