Russia will not release the U.S. journalist currently behind bars in Moscow who they accuse of spying. 

An appeal by Wall Street Journal reporter Evan Gershkovich has been denied, and he will be kept in detention until August. 

Gershkovich, 31, was arrested in late March on charges of espionage while reporting in Russia.

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The United States government has declared Gershkovich wrongfully detained and are demanding Russia release the journalist back into American custody.

The Wall Street Journal revealed in April that Gershkovich, their Moscow bureau reporter, was arrested by the Russian government's Federal Security Service on charges of espionage on behalf of the United States. 

The publication has vehemently denied these charges while several of Gershkovich’s colleagues have defended his integrity.

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Gershkovich was originally detained by Russian forces on Mar. 29 in the city of Yekaterinburg after being accused of "trying to obtain secret information," "on the activities of one of the enterprises of the Russian military-industrial complex." 

At the time, the Russian Foreign Ministry previously recognized him as an accredited journalist. 

Gershkovich also worked as a reporter for Agence France-Presse and the Moscow Times as well as a news assistant at the New York Times.

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On April 27, the State Department issued sanctions against Russia’s top intelligence agency, the Federal Security Service (FSB), along with over Gershkovich's wrongful detainment.

Under Russian law, Gershkovich could be detained in a Russian jail for up to a year based on his charges. He faces up to 20 years in prison if found guilty.

Fox News' Caitlin McFall and Lindsay Kornick contributed to this report.