My Soviet school built a mesh fence around its yard. Every week, tardy kids who wanted to cut through the yard tore a hole in the fence. Every weekend, the administration fixed it. But the hole would reappear the morning after. This went on forever. I wish U.S. President Donald Trump, the fence builder of the West, had gone to my school.

The Soviet Union was a country of fences, barriers and walls. Everything was prohibited, locked and guarded. Warning signs were phrased in no uncertain terms: "Do Not Enter: Death!" "Strangers Are Forbidden." "The Border Is Closed."

Barriers didn't stop people from ignoring the warnings. But they complicated things. To steal bricks and cable from construction sites, citizens removed planks from wooden fences or climbed over concrete ones, at the risk of being scratched by rusty nails or barbed wire, bitten by guard dogs or even shot at with rock salt. Construction materials were in short supply, but people needed them and not everyone could pay black-market prices. For intruders, fences were not such a big deal.