Ukrainian Traitor Who Directed Yavoriv Strike Dies in Prison

Oleksandr Kostornyi, who was convicted of high treason for correcting the trajectory of a Russian missile strike on the Yavoriv military training range in western Ukraine, died in prison in June 2026. The death was reported publicly on October 5.

The Crime

The Yavoriv International Center for Peacekeeping and Security was one of the highest-profile targets of the early phase of Russia's full-scale invasion. The facility had hosted NATO training exercises and foreign military personnel, and its destruction was a significant Russian objective.

Kostornyi was found to have acted as a spotter, providing real-time targeting data to Russian forces to improve the accuracy of the strike on the base. He was convicted under Ukraine's treason laws and sentenced to 15 years in prison.

Death in Custody

Kostornyi died while serving his sentence in June 2026. The circumstances of his death were not specified in initial reports. His death closes a chapter in one of the more prominent wartime espionage and treason cases in Ukraine.

Ukraine has prosecuted numerous cases of alleged Russian agents and collaborators throughout the war. Courts have handed down a range of sentences, from lengthy prison terms to life sentences, for those convicted of providing targeting assistance to Russian forces.