Russia's ambassador to Peking at the time [the early 1960s], Chevonenko, told us that Moscow instructed him to try to refuse Chinese food exports, and that Russia had sometimes declined to accept shipments of grain. The Russians knew only too well about the famine. "You didn't have to do any investigation," Chervonenko said. "It was enough just to drive in from the airport. You could see there were no leaves on the trees." On one occasion, when the Chinese said they were going to increase meat shipments, the Russians asked how. The answer was: "None of your business!"
-- Jung Chang and Dan Halliday, Mao: The Unknown Story, 2005