Ukraine’s Volodymyr Zelensky transformed from comedian-president to charismatic war leader. Historians might contend that the Russo-Ukrainian War is a leftover from the surprising, peaceful end of the Soviet empire in 1991. Russia’s Vladimir Putin has never accepted Ukraine’s independence and sovereignty. At age 70, Mr. Putin is determined to restore Greater Russia before Ukraine turns fully to the West. A U.S. intelligence official told me that when an American emissary warned Mr. Putin against an attack late last year, the aging autocrat replied, “What choice do I have?” In the face of resistance, Mr. Putin will double down.

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