In his nearly 15 months in Moscow’s infamous Lefortovo prison, Evan Gershkovich has plowed through Russian literary classics like “War and Peace,” and played slow-moving chess by mail with his father in the United States. He tries to keep himself in shape during the hourlong exercise period he is permitted each day.

Friends who correspond with him describe Mr. Gershkovich, a Wall Street Journal reporter, as positive, strong and rarely discouraged, despite facing the official wrath of President Vladimir V. Putin’s Russia. He went on trial Wednesday, facing up to 20 years in prison on an espionage charge that he, his employer and the U.S. State Department vehemently deny.

“He may have ups and downs like everyone else, but he remains confident in himself, in his rightness,” said Maria Borzunova, a Russian journalist. She is among a small group of Mr. Gershkovich’s friends who have organized the herculean task of taking thousands of letters from well-wishers and translating them into Russian, to smooth their approval by prison censors.

At the heart of Mr. Gershkovich’s ordeal is a void — the absence of any evidence made public by the Russian authorities to support their claim that he was a spy. Nor is any likely to emerge from his trial in Yekaterinburg, which has been declared secret, with any observers barred from attending, and his lawyers prohibited from publicly revealing anything they learn.

Shortly before the trial was expected to start at 11 a.m. local time, journalists were allowed to film Mr. Gershkovich, with his head recently shaved, as he stood in a glass cage in the courtroom. The proceedings began shortly afterward, according to a statement from the regional court where the trial was taking place.

“We think that it is a sham trial based on fake charges, therefore the proceedings will be farcical,” Almar Latour, the publisher of The Wall Street Journal, said in an interview. It is impossible to predict how a trial will affect efforts to obtain Mr. Gershkovich’s release, he added.

In Russian trials, conviction is largely a foregone conclusion, especially when — as in this case — the Kremlin has weighed in. The judge hearing the case has boasted to a local news outlet that in a career spanning decades, he has acquitted just four defendants.

For more than five years, Mr. Gershkovich, a U.S. citizen who grew up in New Jersey, roamed Russia as a reporter, growing to love the country, friends say. The Foreign Ministry repeatedly reissued his reporting credentials.

Now he may be Kremlin fodder for a prisoner swap, as other imprisoned Americans have been recently. In hammering out such an exchange, Russia insists that first a trial must be completed, ostensibly putting both sides on equal legal footing.

“He’s a Kremlin chip, and they want to trade him,” said Pjotr Sauer, a reporter for The Guardian newspaper and a close friend of Mr. Gershkovich.

In April 2022, Russia traded Trevor Reed, an American convicted of assaulting Russian police officers, for a Russian pilot imprisoned on cocaine trafficking charges in the United States. In the highest-profile recent case, in December 2022, the United States traded a notorious arms dealer, Victor Bout, for Brittney Griner, an American basketball star imprisoned for cannabis possession.

Asked in a television interview in February about Mr. Gershkovich’s fate, Mr. Putin said negotiations were underway, but he mentioned seeking further concessions. He suggested that he might be willing to trade the reporter for Vadim Krasikov, a Russian sentenced to life in prison in Germany for the brazen 2019 murder of a Chechen former separatist fighter in a downtown Berlin park.

Mr. Putin told foreign wire services this month that a dialogue between intelligence agencies was the best way to resolve such issues. A senior Russian diplomat said that negotiations were being conducted through a dedicated, secret channel.

Mr. Gershkovich, 32, was detained in Yekaterinburg, just east of the Ural Mountains, in March 2023. Prosecutors, in their vague statements on the case, have said that “under instructions from the C.I.A.” and “using painstaking conspiratorial methods,” he “was collecting secret information” about a factory that produces tanks and other weapons.

Mr. Gershkovich had been part of a coterie of young Western and Russian journalists based in Moscow. They took their role of explaining Russia to outsiders seriously: constantly working to improve their command of the language, traveling extensively and sharing a traditional weekend cottage in Peredelkino, a hamlet on Moscow’s outskirts known as a retreat for writers.

Mr. Gershkovich, raised by Soviet émigré parents, adopted the name Vanya, and relished Russian rituals like saunas and mushroom hunting, along with sports including soccer and skiing, friends said. His family was not available to comment on the trial, said Ashley Huston, a Journal spokeswoman.

But the climate for journalists in Russia turned threatening with the country’s invasion of Ukraine in February 2022. The Kremlin passed draconian laws limiting how the war could be described, and shuttered numerous independent Russian outlets. Mr. Gershkovich was among the many journalists who left the country, but he returned periodically to gauge how the conflict was changing Russia.

Given that no Western correspondent had been charged with spying since the Soviet era, the prospect of imprisonment seemed troubling but remote. Mr. Gershkovich’s arrest crossed a line, Ms. Borzunova said, making it clear that all reporters, not just Russians, were at risk.

“We thought that official accreditation meant something,” she said, “but it doesn’t.”

Lefortovo has long been the main facility for holding dissidents and other high-profile detainees in the capital. Prisoners are kept in their cells 23 hours a day, with one hour of “exercise” time in a similarly cramped space that is open to the sky.

Mr. Gershkovich has met with his lawyers, and the U.S. ambassador, Lynne Tracey, has been allowed occasional visits. The State Department has declared him “wrongfully detained.”

His friends swung into action with a letter-writing campaign to keep him connected to the outside world. It has drawn more than 5,000 letters from around the world written by everyone from grandmothers to grade school pupils. Many people detailed difficult experiences they had endured, said Polina Ivanova, a reporter for The Financial Times.

Peter Molthoff, from the Netherlands, described spending two years in a Nazi prison camp during World War II. Now 99, he wrote that he knew what Mr. Gershkovich was going through, encouraging him to stay strong and noting that he, himself, had built a beautiful life after his release.

Mr. Gershkovich’s friends have been inspired partly by his consistently high morale. In pretrial court hearings, standing in a holding cage for defendants, he usually greeted his fellow reporters with a grin and sometimes held his hands in the shape of a heart.

He has maintained a sense of humor, suggesting in letters to friends that prison gruel was no worse than some of his childhood meals. Mr. Gershkovich, who once worked in a clerical role in The New York Times’s newsroom, had been a cook briefly before entering journalism. His friends prepare weekly care packages to supplement the lack of fruit and vegetables in Russian prisons, adding candy for his birthday.

He has returned the favor, making sure to send them birthday or holiday greetings. He asks friends to update him about their lives, even encouraging them to send him separate letters describing the same social events. “Like a real journalist, he wants different sources,” said Mr. Sauer.

A voracious reader, Mr. Gershkovich scoured the prison library for some of the thick, foundational tomes of Russian literature, including Tolstoy’s “War and Peace” and Vasily Grossman’s “Life and Fate.” He also reads poetry and works about people behind bars. Initially his friends tried to read the same texts, to run a book club by correspondence, said Ms. Ivanova, but they could not keep pace with him.

Time in prison has polished his command of the language. “He had baby Russian when he arrived, there was no slang, now it is lyrical, beautiful,” said Mr. Sauer.

From the moment Mr. Gershkovich was arrested, his friends said they anticipated a long ordeal, given the experience of others.

Paul Whelan, an American charged with espionage, has been jailed since 2018. Marc Fogel, a U.S. citizen who taught at the Anglo-American School in Moscow, was convicted of drug smuggling and sentenced in 2022 to 14 years in a penal colony. Alsu Kurmasheva, an editor for Radio Free Europe/Radio Liberty and a dual Russian American citizen, faces an extended sentence on various charges.

“We realized that this was going to be a marathon,” said Ms. Borzunova, “that this was not going to be resolved quickly, that we had to prepare to tell this story for a long time, that he was a hostage of the Russian regime, that he was detained for his work.”