Russian leaders rejoined an agreement on Wednesday to export Ukrainian grain. They had pulled out of the deal on Saturday, citing an alleged drone attack on their Black Sea fleet.

Negotiators agreed in July to allow the safe passage of grain out of ports in southern Ukraine to world markets. But Russian officials said the Ukrainians broke the terms. They demanded guarantees that those forces would not use the Black Sea grain corridor for military operations.

"We reserve the right to withdraw from these agreements if the Ukrainians breach these guarantees," said Russian President Vladimir Putin.

Ukrainian President Volodymyr Zelenskyy accused the Russians of "blackmail." "If there were no Russian attacks on Ukraine, there would not even be a ghostly threat of a global food crisis," he said.

Turkish President Recep Tayyip Erdogan helped broker the original agreement, and he helped salvage the deal. He said diplomats need to increase their efforts to end the war.