New Delhi, Aug. 12 -- WASHINGTON - The phone call that stopped Ukraine's Black Sea drone campaign came on July 31, when US Vice President JD Vance told Ukrainian President Volodymyr Zelensky directly that Kiev must halt all attacks on the Caspian Pipeline Consortium facilities and non-Russian tankers. Zelensky, facing explicit American pressure on oil infrastructure he had been targeting, did not resist.

Ukraine had agreed, at Washington's request, to suspend strikes against the CPC infrastructure used to deliver Kazakh oil to global markets.

"We very carefully listen to our American partners," a senior Ukrainian official told the Financial Times, declining to give their name. Since the call, Kiev has not struck any oil tankers near the...