I was walking with my wife here in a cold, intermittent rain. I had just visited the Soviet War Memorial in the Tiergarten, not far from the Brandenburg Gate. We were quiet after standing before the final resting place of thousands of men who had once been our allies in the fight against the Nazis. We headed toward the Ebertstrasse, where the Berlin Wall once divided the city, and where tourists and students now milled about taking selfies in places they would have been arrested or even shot within my adult lifetime.

Perhaps it was the weather, or perhaps it was the cemetery’s grim but majestic statue of the Red Army soldier standing guard over his fallen comrades, but I found myself contemplating the chilling thought that if we had destroyed the planet in a thermonuclear war, it would likely have started not far from where my wife and I were now strolling arm in arm.