A Russian court rejected US journalist Evan Gershkovich’s appeal for release on Thursday ahead of his trial on espionage charges. In a closed-door hearing, the Moscow City Court refused to overturn a May decision from the Lefortovo Court of Moscow, which extended Gershkovich’s pretrial detention through August 30.

Because of the alleged secrecy of the material Gershkovich is accused of handling, the courtroom proceedings took place behind closed doors. Gershkovich was joined by his legal counsel, parents and a US diplomatic mission led by US Ambassador to Russia Lynn Tracy.

In a statement to the press after the court proceedings, Tracy said she was “extremely disappointed” by the ruling. She continued, “He is an innocent journalist who was carrying out journalistic activities and has been wrongfully detained. Such hostage diplomacy is unacceptable and we call on the Russian Federation to release [Gershkovich].”

The Wall Street Journal (WSJ), the newspaper that employs Gershkovich, also commented on the court’s ruling. They said, “Although the outcome was expected, it is no less an outrage that his detention continues to be upheld. Evan has been wrongfully detained for more than 12 weeks for nothing more than doing his job as a journalist. We continue to demand his immediate release.”

Russian state security forces first arrested Gershkovich on March 30 and then formally charged him on the basis of collecting “information constituting a state secret about the activities of an enterprise within Russia’s military-industrial complex.” On April 18, the Lefortovo Court of Moscow rejected Gershkovich’s attempt to appeal the charges against him. He was initially ordered to remain in a Russian detention facility until May 29, but that has since been extended to August 30.

Gershkovich is the first US journalist charged with espionage since the Cold War. Both the US government and the Wall Street Journal maintain that Gershkovich is wrongfully detained and call for his immediate release.