A Russian court sentenced two Ukrainian men to 23 years in prison Wednesday for trying to sabotage power lines near nuclear plants in Moscow and Saint Petersburg, according to a court spokesperson.

Oleksandr Maistruk and Eduard Usatenko, born in 1978 and 1974, were accused of attempting to blow up more than 30 pylons connected to the Leningrad and Kalinin nuclear power plants, said Saint Petersburg court spokesperson Daria Lebedeva on Telegram.

Authorities claim the pair, working on behalf of Ukraine’s Foreign Intelligence Service, carried out the attacks on May 8, a day before Russia’s Victory Day.

“The defendants wanted to shut down the nuclear reactors,” Lebedeva said. The men successfully detonated one pylon and planted explosives under 11 others, causing more than $100,000 in damages.

The Leningrad plant is located west of Saint Petersburg, while the Kalinin plant is around 250 kilometers north of Moscow. Both men were fined 900,000 rubles ($9,500) in addition to their prison terms.

Sabotage incidents have surged across Russia since its February 2022 invasion of Ukraine, with most blamed on agents linked to Kyiv.

Both nations have accused each other of targeting nuclear plant security throughout the conflict. Moscow currently occupies Ukraine’s Zaporizhzhia plant, Europe’s largest nuclear station.

The International Atomic Energy Agency has warned both sides against targeting power plants, stating they should never be considered legitimate targets.