Andrew Brunson is an American pastor who has lived in Turkey for many years. (DHA-Depo Photos/AP)

An American pastor facing decades in prison on terrorism-related charges in Turkey is scheduled to appear in court for the first time on Monday, in a case that could test the Trump administration’s ability to sway its increasingly estranged Turkish allies.  

 The pastor, Andrew Brunson, was detained in October 2016 during a large-scale wave of arrests by the authorities after a failed coup attempt in Turkey. A formal indictment — presented a year and a half after Brunson’s arrest — accused him of associating with the coup plotters and other offenses, based on evidence that his lawyer, his advocates and U.S. officials have dismissed as groundless.

White House officials, including Vice President Pence, have repeatedly pressed Turkey to release him.    

His supporters say they fear that Brunson is being used as a bargaining chip during ongoing and testy negotiations over several disputes between the government of Turkish President Recep Tayyip Erdogan and the Trump administration.   

 A central argument between the two countries concerns the fate of a Turkish cleric, Fethullah Gulen, who lives in exile in Pennsylvania. Turkish officials have described Gulen as the architect of the failed coup in the summer of 2016 and demanded his extradition from the United States. American officials contend that the Turkish government has failed to provide enough evidence to warrant extradition. 

 In a speech last year, Erdogan appeared to suggest that Brunson could be traded for Gulen. “Give us that pastor,” he said, “and we will do what we can in the judiciary to give you this one.”  

 It is just one of several issues dividing Turkey and the United States, which have also been bitterly at odds over U.S. policies during the civil war in Syria. The Turkish government has strongly objected to U.S. military support for Syrian Kurdish fighters associated with Turkey’s Kurdistan Workers’ Party, or PKK, a separatist group that the U.S. and Turkey have classified as a terrorist entity.   

 Brunson, 50, a Christian missionary from North Carolina, has lived in Turkey for 23 years. He was detained in October along with his wife, Norine Brunson, though she was released.  

 The indictment, based on evidence provided in part by three secret informants, accuses Brunson of acting in coordination with Gulen’s organization as well as the PKK. It also accuses him of attempting to convert Kurds to Christianity.

 Brunson’s Turkish lawyer, Ismail Cem Halavurt, dismissed the evidence against his client, including a charge that Brunson had met with a senior member of the Gulen movement. “This is only a claim by the secret witness, but the secret witness is lying,” he said.  

 “There is no substantial evidence other than the claims of the secret witness,” he said. 

In the months that he has languished in jail, Brunson has lost 50 pounds and missed the marriage of his daughter, said CeCe Heil, the executive senior counsel at the American Center for Law and Justice, a conservative group started by televangelist Pat Robertson that is known for defending Christian causes before the Supreme Court. Jay Sekulow, the group’s chief counsel, is also President Trump’s personal lawyer.

“Hopelessness has overtaken him,” she said.  

But the formal issuing of the indictment last month, and the speedy scheduling of the trial, was a potentially positive sign — providing Turkish officials with the kind of judicial process they have said was a prerequisite to resolving Brunson’s case.

 “Hopefully that is an indicator that we are moving in the right direction toward Pastor Brunson’s release,” Heil said.