A senior aide to Ukrainian President Volodymyr Zelensky said Kyiv had nothing to do with an armed operation in Russia's Belgorod region on Monday.
"Ukraine is watching the events in the Belgorod region of Russia with interest and studying the situation, but it has nothing to do with it," presidential adviser Mykhailo Podolyak tweeted.
"As you know, tanks are sold at any Russian military store, and underground guerrilla groups are composed of Russian citizens."
In a written statement to Reuters, Podolyak said Ukraine's military operates only on Ukrainian territory and echoed Ukrainian military intelligence in blaming Russian partisans for the incursion.
"The Russian liberation movement can become something that will contribute to the correct end of the war in Ukraine and significantly speed up the beginning of transformational events in the Russian political elite," he said.
Zelensky aide blames Russian resistance events
"The Russian violent resistance movement, whose architects are exclusively citizens of Russia itself, is gradually coming out of the underground. They are independent in their decisions, have certain experience, and are free from fear."
Podolyak said Russia's war on Ukraine was "gradually returning to Russia itself."
"The authorities are losing control over the regions and the situation in general. And this is a window of opportunity for any internal protest movements," he said.