Not long after Russia launched its invasion of Ukraine, a year ago this week, Ukrainian President Volodymyr Zelensky found himself in a safe room beneath Kyiv’s government complex with the voice of the Belarusian president booming over the phone. Alexander Lukashenko, one of the Kremlin’s key allies, was inviting a delegation of officials to Minsk to negotiate an end to the war that Russia had launched just three days earlier, according to Andriy Sybiha, the deputy head of Ukraine’s presidential office, who was in the room for the call. Zelensky was incensed at the invitation to another negotiation — recalling...