This was announced by Chief of Staff of the Head of SBU Oleksandr Tkachuk at a briefing, Censor.NET informs citing a slide presentation of Tkachuk's address, published by SBU's press service.
According to him, in August 2015 the Armed Forces of Ukraine together with secret services liquidated 'Rusich' sabotage group of the terrorists, mostly comprising citizens of Russia, including career soldiers.
As of today, the number of Russian military in the Donbas totals 6,000 people, Tkachuk added.
SBU press service also published personal data of several Russian soldiers killed in the Donbas.
Sergey Vorobiev, the 16th separate special purpose brigade of GRU, killed near Debaltseve, survived by his family and children.
Dmitriy Dutov, volunteer from Sochi. Killed near Debaltseve. Survived by his child.
According to available data, more than 1,600 soldiers from 26 military units of Russia have been killed. This information is not complete, the losses are much higher, the authority stressed.
SBU says that Russia deploys its elite military units for the war in the east of Ukraine, including career officers of the special forces of GRU, marines, motorized rifle soldiers, tankmen, and artillerymen. They also noted that Ukrainian secret services have operative information on almost every Russian soldier fighting in the Donbas.
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"We address mothers and wives of Russian military: stop your kids, your men, and fathers of your children. War in the Donbas is not Syrian safari - they would get killed!" SBU added.