Vasylenko was arrested in October 2019 on suspicion of smuggling unspecified dangerous materials, weapons, and valuable cultural items.
The charge was later amended to espionage.
The materials in the case are classified. No other details have been made public.
Vasylenko has not commented publicly on the case because of the classification.
Russia has arrested and convicted several Ukrainian nationals on espionage charges in recent years.
Relations between Moscow and Kyiv have been tense since 2014 when Russia annexed Ukraine’s Crimean Peninsula and began backing separatists in the conflict in eastern Ukraine, which has left more than 13,200 people dead.