Metin Topuz' arrest in October 2017 exacerbated tensions between Washington and Ankara, already strained over U.S. support for Kurdish fighters in Syria, Turkey's plan to buy a Russian defense system, and the U.S. jailing of an executive at a Turkish state bank in an Iran sanctions-busting case.
The Istanbul court ruled to keep Topuz, a translator and fixer for the Drug Enforcement Agency, in detention until trial hearings scheduled for March 26, Anadolu said.
Topuz was arrested over alleged links to the network of U.S.-based cleric Fethullah Gulen, whom Turkey accuses of a coup attempt in 2016. Gulen denies that.
The indictment seeks life imprisonment for Topuz on charges of "attempting to overthrow the constitutional order," spying and "attempting to remove the government."