Three Crimean natives have been convicted of high treason and sentenced to between 12 and 17 years in a strict-regime penal colony for setting up surveillance equipment to help Ukrainian intelligence spy on Russian warships, Russian authorities said.
The Russian Federal Security Service, known as the FSB, stated through state news agency TASS that the men installed remote listening devices in Sevastopol and Novorossiysk to monitor naval radio frequencies over the internet.
According to the FSB public relations centre, the technical equipment allowed Ukrainian forces to gather precise data on naval combat readiness, vessel locations, and command plans in real time. Officials said the intelligence was used to direct missile strikes and uncrewed aerial vehicle attacks against Russian targets.
Surveillance in Black Sea ports
The surveillance gear was set up near key naval facilities in Sevastopol and Novorossiysk. Sevastopol is a major port city on the southwestern coast of the Crimean Peninsula that serves as the principal base for Russia's Black Sea Fleet. Novorossiysk is a major commercial harbour and naval base located on the eastern Black Sea coast in Krasnodar Krai.
The FSB said the three suspects were recruited by Ukrainian military intelligence to gather operational data on the Black Sea Fleet, which commands surface warships, submarines, and naval aviation across the region.
Officers from the FSB unmasked and arrested the three men following an investigation into the radio monitoring network. The Krasnodar Regional Court and the Sevastopol City Court found all three guilty of state treason, handing down sentences ranging from 12 to 17 years in strict-regime penal colonies.
Related treason convictions
Russian courts have increasingly handed down lengthy prison terms in cases involving alleged espionage and sabotage linked to Ukrainian military services or affiliated volunteer units.
In a separate case, Russian state media reported that Yekaterina Malovechkina, a resident of Zabaykalsky Krai in eastern Siberia, was sentenced to 24 years in prison for blowing up a train on August 24, 2025. Russian investigators said she carried out the attack under instructions from the Freedom of Russia Legion, a paramilitary group that is officially designated as a terrorist organization and banned in the Russian Federation.
