When Vladimir Putin takes to the stage on Tuesday to commemorate the Soviet victory over Nazi Germany, his speech on Red Square will have been preceded by a turbulent week in which drones attacked the Kremlin and one of his top war leaders threatened mutiny. The dramatic footage early last Wednesday of two drones flying over the walls of the Kremlin, its historical seat of power, exposed vulnerabilities in the heart of the Russian capital, putting Moscow on edge. The authorities have banned the use of drones and started jamming GPS signals, leading to taxis appearing to be in the...