The man filmed an air defence system in Podolsk, about 40km south of Moscow, in April and sent images along with geographical data “to his Ukrainian mentors to guide a drone strike against this military site”, the Russian investigative committee said.

Russia has launched a crackdown on critics of what it calls a special military operation in Ukraine in February 2022, with trials for treason, terrorism, extremism, sabotage or espionage multiplying.

The committee said the man also brought weapons from Ukraine to Russia in 2017 to prepare attacks in several regions, including Bryansk and Kursk and Belgorod, which all border Ukraine.

The court found him guilty of preparing an attack, arms trafficking and complicity in terrorist activities, it added.

In addition to treason trials, thousands of people have been sanctioned, threatened or imprisoned in Russia since 2022 because of their opposition to the conflict in Ukraine.