Over the course of the summer, Russian attacks have been pushing ever deeper into European territory. On August 11, military divers destroyed two drones floating off the coast of Romania near a €4 billion (US$4.7 billion) energy project. Nine days later, Bucharest scrambled two F-16s to take out a maritime drone near the same Black Sea gas platform with hundreds of workers on board. Earlier that month, German police detected an armed UAV at Leipzig airport, while this week Nato jets downed...