(Reuters) – John Walker Lindh, the American captured in Afghanistan in 2001 fighting for the Taliban, was released early from federal prison on Thursday, the Washington Post reported, citing Lindh’s lawyer.

Lindh, who was 20 years old when he was captured, left prison in Terre Haute, Indiana, on probation after serving 17 years of a 20-year sentence, the newspaper said.

Now 38, Lindh is among dozens of prisoners to be released over the next few years after being captured in Iraq and Afghanistan and convicted of terrorism-related crimes following the attacks on the United States by al Qaeda on Sept. 11, 2001.

FILE PHOTO: A picture of John Walker Lindh is shown on the attendance register of the madrassa (Islamic school) Arabia Hassani Kalan Surani Bannu, in Bannu in Pakistan, January 26, 2002. REUTERS/Haider Shah/File Photo

His release brought objections from elected officials who asked why Lindh was being freed early and what training parole officers had to spot radicalization and recidivism among former jihadists.

U.S. Secretary of State Mike Pompeo called Lindh’s release “unexplainable and unconscionable.”

“There’s something deeply troubling and wrong about it,” he said on Fox News on Thursday morning.

Leaked U.S. government documents published by Foreign Policy magazine show the federal government as recently as 2016 described Lindh as holding “extremist views.”

“What is the current interagency policy, strategy, and process for ensuring that terrorist/extremist offenders successfully reintegrate into society?” asked U.S. Senators Richard Shelby and Margaret Hassan in a letter to the Federal Bureau of Prisons.

Lindh’s parents, Marilyn Walker and Frank Lindh, did not respond to requests for comment and Lindh’s lawyer, Bill Cummings, declined to comment.

Melissa Kimberley, a spokeswoman for the prison in Terre Haute, could not immediately be reached for confirmation of the Post’s report.

U.S.-born Lindh converted from Catholicism to Islam as a teenager. At his 2002 sentencing, he said he traveled to Yemen to learn Arabic and then to Pakistan to study Islam.

FILE PHOTO: Undated handout image of American Taliban John Walker Lindh, distributed February 5, 2002. American Taliban fighter John Walker Lindh, described by a prosecutor as a “committed terrorist” who abandoned his country, is to be released early from a federal prison while some U.S. lawmakers worry he still poses a security risk.. REUTERS/Handout/File Photo

He said he volunteered as a soldier with the Taliban, the radical Sunni Muslim group that ruled most of Afghanistan from 1996 to 2001, to help fellow Muslims in their struggle or “jihad.” He said he had no intention “to fight against America” and never understood jihad to mean anti-Americanism.

Lindh told the court he condemned “terrorism on every level” and attacks by al Qaeda leader Osama bin Laden were “completely against Islam.”

But a January 2017 report by the U.S. government’s National Counterterrorism Center, published by Foreign Policy, said that, as of May 2016, Lindh “continued to advocate for global jihad and to write and translate violent extremist texts.”

NBC News reported that Lindh wrote a letter to its Los Angeles station KNBC in 2015 expressing support for Islamic State, saying the Islamic militant group was fulfilling “a religious obligation to establish a caliphate through armed struggle.”

(Reporting by Andrew Hay in Taos, New Mexico; Additional reporting by Jonathan Allen; Editing by Bill Trott)