When I served as U.S. ambassador to Russia, the embassy in Moscow held a regular safety exercise called the “duck and cover drill.” The drill is designed to save lives in the event of an attack, and our team practiced it so often that even embassy children could recite the announcement by heart. Through repetition, our reaction to the jarring siren became an ordinary part of the job.

Having now completed my tenure in Moscow, it strikes me that the “duck and cover drill” is a fitting metaphor for the defensive posture we as...