The signs of the times are everywhere. Estonia is erecting a 2.5-meter-high metal mesh fence reinforced with barbed wire along much of its border with Russia—and backing it up with high-tech drones, sensors, radars, and cameras. Neighboring Latvia has announced plans to build fences along its eastern frontier. Poland plans to build new state-of-the art watchtowers on its border with Russia’s Kaliningrad exclave.
