The Mayor of Kyiv, Vitali Klitschko, has told the BBC the Russian public will eventually realise their young soldiers are dying for nothing more than Russian President Vladimir Putin's ambitions.
The former world heavyweight boxing champion was attending the funeral of a well-known 24-year-old anti-corruption activist when the remarks were made, reports BBC.
Volunteer soldier Roman Ratushny was killed in Izyum, in the Kharkiv region, on 9 June.
Mayor Klitschko, who won legions of fans across the world during his long record-breaking career, said the Russian leader was destroying millions of lives in both Ukraine and his own country.
"This is also a tragedy for Russians and for the Russian Federation. The people do not understand that right now, but I am sure they will realise very soon the reality. The Russians die - for what? The ambition of Putin?"
The mayor was among hundreds of mourners who turned out to pay their respects to Mr Ratushny - who came to prominence during pro-democracy protests in 2013 against the pro-Moscow former Ukrainian government.