MOSCOW—The sudden, unexplained illness of Alexei Navalny comes in the midst of what has been a difficult year for Russia’s leader, President Vladimir Putin.
Mr. Navalny has for years been the Kremlin’s most effective critic, with some four million followers on his campaigning YouTube channel. He fell ill on a flight from Siberia to Moscow on Thursday after drinking a cup of tea at the airport that his supporters believe was laced with poison.
Doctors treating him in Omsk, the city where the plane made an emergency landing, said they hadn’t found any toxins in his system and at first refused to hand him over to a German team waiting to medevac him for treatment in Germany, saying he was too unstable to move. Later, Mr. Navalny was cleared to fly Friday after his wife published a letter asking Mr. Putin for help.
Political analysts said it is unclear what role if any the Kremlin might have had in harming Mr. Navalny. But in the short term it could have a chilling effect among Mr. Putin’s opponents at a time when he has been facing new challenges to his authority, from a wave of protests in Russia’s Far East to upheaval on its western border, where mass protests in Belarus are threatening to chase one of his closest allies from power.
“I can’t say that this opposition will disappear,” said Andrei Kolesnikov, chair of the Russian Domestic Politics and Political Institutions Program at the Carnegie Moscow Center. “But at the same time, we must admit that we describe the political landscape of Russia as a permanent adverse relationship between Navalny and Putin.”