The Kremlin has come under international pressure to allow shipments to resume as part of a deal brokered by the United Nations and Turkey on July 22 aimed at eliminating food shortages in countries that have traditionally bought grain and other products from Ukraine, a leading producer of agricultural products. After a visit on Friday to the port of Chornomorsk, near Odessa, Volodymyr Zelensky, the Ukrainian president, said his country was ready to begin exports, although he said it was not