It was a remarkable moment in the war in Europe: President Volodymyr Zelensky of Ukraine gave a 90-minute-long Zoom interview on Sunday to four prominent journalists from Russia, the country invading his. Hours later, the Kremlin responded. A government statement notified the Russian news media “of the necessity to refrain from publishing this interview.” Journalists based outside Russia published it anyway. Those still inside Russia did not. The episode laid bare the extraordinary, and partly successful, efforts at censorship being undertaken in Russia by President Vladimir V. Putin’s government as his bloody invasion of Ukraine enters its second month, along...