Russian political scientist Hleb Pavlovsky, a former adviser to the Kremlin, died on Monday at the age of 71 after a serious illness, writes The Moscow Times.

This was reported by Simon Kordonsky, head of the Department of Local Self-Government at the Moscow Higher School of Economics, to the Vedomosti business publication.

Pavlovsky was an influential figure in Russian politics during the first decade of President Vladimir Putin’s rule, serving as his adviser and “political technologist” since 1996.

He was also one of the leaders of Boris Yeltsin’s campaign in 1996, and also participated in the campaign of Viktor Yanukovych in the 2004 presidential elections of Ukraine.

Pavlovsky was fired from the president’s administration in 2011, reportedly for supporting the re-election of then-president Dmitry Medvedev instead of Putin’s return to the presidency.

After that, he joined the opposition.

Pavlovsky was a sharp critic of Putin and the war in Ukraine, while continuing to stay in Moscow. In a recent interview, he stated that the war started by Putin will continue.

“Putin is used to being lucky. This is very dangerous for the player as he starts to believe that fate is on his side. When you play Russian roulette, you feel that God is on your side until you hear a shot,” Pavlovsky told the Financial Times after Russia invaded Ukraine.

Pavlovsky was born in Odessa and was a Soviet-era dissident who served time in internal exile in the northern Republic of Komi in the 1980s.