Editor's note: This article initially referred only to a report by Ukrainska Pravda, citing anonymous intelligence sources. It was updated once Ukraine's military intelligence published a video confirming that a Russian fighter jet was set on fire.
A Russian Su-34 fighter jet was lit on fire overnight on Jan. 4 at the Shagol airbase in Chelyabinsk, Russia, Ukraine's military intelligence agency (HUR) said, publishing a video of the burning plane.
The HUR did not explicitly claim responsibility for the incident, saying that "the causes of the plane's ignition are being determined."
Earlier on Jan. 4, Ukrainska Pravda reported that the HUR was behind the torching, citing an undisclosed intelligence source.
While the military intelligence said that the aircraft burnt down, the full extent of damage to the plane, which costs at least $50 million, is not apparent from the published footage.
The jet belonged to the 21st Mixed Aviation Division of the Russian Air Force, the HUR said.
Ukraine's Air Force Commander Mykola Oleshchuk announced on Dec. 22 that his troops had downed three Russian Su-34 aircraft on the southern front.
Three days later, the Air Force reported the downing of another Su-34 plane and a Su-30 fighter jet.
The Institute for the Study of War (ISW) reported on Dec. 24 that Russia was decreasing its aviation activity after the string of repeated aircraft losses.
Chelyabinsk is located almost 2,000 kilometers east of the Ukrainian border.
Ukrainian sabotage attacks on Russian infrastructure have been reported even farther away, such as the derailing of a freight train on Dec. 1 in the far eastern republic of Buryatia, almost 5,000 kilometers from Ukraine.