(Bloomberg) -- Ukrainian intelligence was behind the explosion of a freight train in Russia’s Far East, according to an official familiar with the operation, an attack that would extend the agency’s reach deep into Siberia.  

Agents from the Security Service of Ukraine, or SBU, targeted a section of the Baikal-Amur rail link using four explosive devices, the official said on condition of anonymity. The train was moving through a tunnel near Severomuysk, northeast of Lake Baikal. 

The SBU believed the link has been used to ferry military supplies, the official said. The Baikal-Amur and Trans-Siberian railroads, running north of the Chinese border, make up Russia’s two main transport arteries through Siberia and carry cargo and commodities shipments as well as passenger traffic. Last year they handled 149 million tons of goods. 

State-owned Russian Railways said on Telegram that a train carrying fuel through a tunnel in Russia’s Buryatia region caught fire, requiring it to redirect rail traffic along an alternative route, causing a “slight” delay. 

An attack more than 4,000 miles east of Kyiv would send a message about the Ukrainian military’s reach even as the country grapples with a stalled counteroffensive and concerns over waning support from its allies. 

The SBU has taken responsibility for a number of targeted strikes behind the front lines over the course of the war, including a naval drone attack on a Russian missile carrier in Crimea last month. Within Russia, Ukrainian special forces targeted a power station in the Belgorod region with drones, Interfax reported in October, citing the SBU.

--With assistance from Greg Sullivan.

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