Ukrainian partisans claimed on July 5 to have successfully sabotaged a railway line near the Russian city of Yekaterinburg, halting trains being used to transport North Korean ammunition.
In a post on Telegram, the ATESH partisan group said the operation was carried out on the Trans-Siberian railway east of the Ural Mountains.
It also claimed Russian journalists were prevented from accessing the scene of the operation and repairs were only allowed to be carried out after Russia's Federal Security Service (FSB) had visited.
A video accompanying the post appeared to show an explosion at the scene of the sabotage.
"And we want to remind you once again that the railway will explode even more often as long as ammunition is being carried along it," ATESH added.
The Kyiv Independent could not verify the claims.
North Korea has sent containers to Russia that could contain as many as 4.8 million artillery shells, South Korean Defense Minister Shin Won-sik said in an interview with Bloomberg published on June 14.
With Russia's military stocks running low due to extensive use in Ukraine, North Korea has been shaping up as Russia's leading weapons supplier.
The ATESH movement claims to be active in both occupied areas of Ukraine and inside Russia itself.
Last week it claimed one of its agents successfully infiltrated a Russian air base and hinted at carrying out sabotage operations.
In a post on Telegram on June 22, the group said it had scouted the Baltimore airfield in Voronezh, around 220 kilometers north-east from the border with Kharkiv Oblast and home to Russia's 47th Guards Bomber Aviation Regiment.
Pictures and videos accompanying the post show several aircraft including a helicopter and what ATESH say are Su-34 fighter bombers, a plane Russia frequently employs to launch missiles at Ukrainian cities.
"In some of them, Russians now have surprises waiting for them," the post reads.
On June 12, the group said a Russian satellite communication station was destroyed in a sabotage attack in Moscow Oblast.
In a video posted by Atesh partisans on Telegram, an Atesh agent is seen pouring a flammable liquid on an R-441 Liven communications satellite. The communications station is seen subsequently catching fire.
The incident allegedly occurred in the Klin district of Moscow Oblast – approximately 85 kilometers (over 50 miles) northwest of the Russian capital.
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