Evan Gershkovich is the first American journalist arrested in Russia on espionage charges since the end of the Cold War.
The Wall Street Journal reporter denies the spying charge, which could lead to a prison sentence of up to 20 years if he is convicted.
Ukraine's plans for a counteroffensive against Russian occupation remain on track, its deputy defense minister said despite an "unprecedented" wave of missile and drone attacks.
“As Americans, we condemn how our fellow citizen, Evan Gershkovich, has been unlawfully arrested and detained by Russian officials,” Rabbi Mendy Mirocznik said.
Gershkovich is the first US journalist detained in Russia on espionage charges since the end of the Cold War.
Employees were able to see which videos affiliated users watched through a dashboard. The employees could also see the users' ID numbers.
Gershkovich was arrested in March and accused of espionage, which he and his newspaper, the Wall Street Journal, deny.
The Kremlin has said Gershkovich, the first US journalist detained in Russia on espionage charges since the end of the Cold War, was caught "red-handed."
The hearing is essentially procedural - about how Gershkovich should be detained as he awaits trial, not about the substance of the charges.
A Moscow court next week will hear an appeal by Gershkovich's legal team against a ruling that he be held in pre-trial detention at Moscow's Lefortovo prison until at least May 29.