Since the very beginning of the war, the Russian Federation has been concealing the presence of Russian military troops in eastern Ukraine. Vladimir Putin signed a decree on classified information about military losses in peacetime during special operations. There is thus no official statistics from Russia on the number of dead there.
However, the JFO press center regularly publishes information about losses in Russia's armed forces. In 2019, 619 losses
of Russian occupation forces were recorded in Donbas, with 49 Russian soldiers killed
in June 2020.
Furthermore, a report
by the Office of the UN High Commissioner mentions 5,650 losses of "armed groups" during the conflict in eastern Ukraine. Also, in Russia, there were investigations
of the deaths of Russian service members in Donbas. However, Russian authorities do not recognize the results of those investigations.
The Russian soldiers that were taken prisoners in Ukraine serve as yet another proof of the aggression. And Russia did recognize these service members by agreeing to an exchange of prisoners.
For instance, in 2016, Nadiia Savchenko was exchanged for two Russian GRU officers
(GRU is Russia's main intelligence directorate) — Yevgeny Erofeev and Aleksandr Aleksandrov. There were other instances
where Ukraine captured
Russian service members : paratroopers, GRU special forces officers, etc.
Finally, the presence of Russians in Donbas is evidenced both by the satellite photos of Russian military convoys in Ukraine and the photos posted by Russian soldiers on social networks.