India, June 5 -- The letter Volodymyr Zelenskyy published on Thursday and sent via diplomatic channels to Vladimir Putin, the United States, and a roster of potential mediating capitals arrived at a precise moment: Putin was on stage at the St. Petersburg International Economic Forum, boasting that Russian forces had taken full control of the Luhansk People's Republic and 85 percent of Donetsk. The timing was not accidental.

Zelenskyy's proposition - a direct, personal meeting with Putin in a neutral country to discuss ending the Russian operation in Ukraine, with a full ceasefire as the stated goal - is the kind of offer that sounds modest on its face while demanding a concession the Kremlin has spent four years refusing to make. The U...