Russia on Friday sentenced a Siberian man to 18 years in prison for planning an arson attack on an army office.It also sentenced two men in a region near Moscow to 16 years for setting railways on fire allegedly on the orders of Ukraine.Moscow saw a wave of arson attacks on military enlistment offices after President Vladimir Putin ordered an unpopular mobilization in 2022, as well as mysterious fires on its railway networksRussia has orchestrated a massive crackdown on dissent, banning criticism of its military offensive in Ukraine.Interfax reported on Friday that a 45-year-old resident of the mountainous Altai region was sentenced by a military court for trying to torch an army office in the regional capital, Barnaul, in November 2023.The FSB security service had accused him of contacting a banned "terrorist organization" and preparing Molotov cocktails on the orders of a "curator."It said he was arrested as he "attempted to commit the terrorist act."He was found guilty of collaborating secretly with a foreign state, taking part in a "terrorist" organization and undergoing training with the aim of carrying out "terrorist" activity.The RIA Novosti news agency later reported that two men in the Kaluga region south of Moscow were handed 16-year sentences for setting fire to relay cabinets operating equipment on the side of railway tracks, accusing them of taking orders from Ukrainian security services.It said the "young people" giving only their surnames Zavalnov and Golodyuk were found guilty of "terrorism" and sentenced by a military court.Moscow also arrested a man in the city of Feodosia in Russian-annexed Crimea on charges of spying for Ukraine.The FSB said the 30-year-old had taken photos of Black Sea Fleet ships and sent them to Ukrainian security services.Authorities launched a treason case.Moscow regularly opens treason cases and accuses its citizens of spying for Ukraine.