The attorney for an American citizen detained in Iraq as an enemy combatant and suspected Islamic State fighter said this week that the United States’s attempts to release him into Syria amount to a “death warrant.”

The American Civil Liberties Union (ACLU) is representing the man who is referred to as “John Doe.” Johnathan Hafetz, the attorney representing Doe, is opposing his release.

“What the government is offering our client is no release — it’s a death warrant. This is a disgraceful way to treat an American citizen,” Hafetz reportedly said in a statement. “Now, our fight for our client’s right to due process has also become a fight for his right to life. We’ll be asking the court to immediately intervene and ensure the safe release of our client.”

NBC reported that court papers said Doe joined the Islamic State in 2014 in Syria. Those papers also said he attended an ISIS training camp, pledged allegiance to its leader Abu Bakr al-Baghdadi, and was listed in an ISIS document as a “fighter.”

However, in court documents, Doe reportedly claimed he entered Syria as a freelance journalist and was kidnapped and forced to work for the Islamic militant group until he fled on a water truck and turned himself in to the Kurds, who then handed him over to the U.S. military.

The Hill reported that the U.S. government said Doe attended ISIS training sessions in Syria starting in March 2015, where he swore allegiance to al-Baghdadi’s deputy, Abu Hafs al-Maghrebi.

He was reportedly assigned to be a fighter in the Zarqawi Brigade, a military unit that “guard[ed] the front lines” in Syria, where he procured fuel for ISIS vehicles, handled expenses and “performed other administrative tasks.” Later, he was tasked with guarding the gate of an ISIS oil field and monitoring personnel who worked on ISIS’s heavy equipment

According to the Hill, Doe’s “planned release — which appears likely to be at least delayed by an ACLU challenge — was announced just two weeks before a federal court is scheduled to hold a hearing on whether the government is holding Doe legally in the first place.”

“The government has effectively admitted that it has no reason to continue detaining our client and that he does not pose a threat,” Hafetz, said in a statement. “But, instead of offering a safe release, they want to dump an American citizen onto the side of the road in a war-torn country without any assurances of protection and no identification.”

In February, George Washington University’s Program on Extremism released a report, titled the Travelers, that stated approximately 300 Americans attempted to join the Islamic State and other radical Islamist groups in Iraq and Syria. Of that group, so far 12 have returned home to U.S. soil and have not yet carried out an attack.

The report points out that “Far fewer foreign volunteers traveled to the Islamic State from the United States than from Europe,” and notes that an estimated 6,000 people, most of them from France, Belgium, Germany, and the United Kingdom, traveled from Europe to join ISIS.