Zelenskiy says Ukrainian drones have effectively closed Russian airspace

Sept 1 (Reuters) - Ukraine's President Volodymyr Zelenskiy warned airlines and insurance companies on Tuesday that the presence of Ukrainian drones had made Russian skies dangerous to use and that they were effectively closed. "Today, we want to warn every airline that uses Russian airspace, every insurer, everyone who still uses key Russian airports: the Russian sky is becoming completely dangerous," Zelenskiy said in his nightly video address. Ukraine poses no threat to civil aviation, he…