There is meanwhile a hoary assumption that China will not let North Korea collapse by suspending the aid it is often supposed to have supplied: it is said to have sent 500,000 tonnes of grain in 2005. Yet household surveys by the WFP last year found no Chinese grain. Even before the proliferation crisis, the International Crisis Group, a think-tank, concluded from research in China that its food aid was minuscule. It is probably now smaller still.
By contrast, North Korea's trade with China (including in food) has grown fast. Last year the country imported over $1 billion-worth of Chinese goods. New UN sanctions against it may change that. This week branches of the Bank of China close to the border stopped doing North Korea-related business, either at their government's decree or because of concerns that their loans could soon go bad.
North Koreans are somewhat more protected today than they were before the great famine of the mid-1990s, in which perhaps 1m died. Many can smuggle, trade, bribe, and grow food on individual plots. Still, according to the UN, a third of North Korean women with children under 24 months are malnourished or anaemic, and more than a third of children under six are stunted. One outlet for the hungry in the 1990s was China, to which 50,000-100,000 North Koreans crossed. That route is now closing, at least for those without money. In the past month, authorities in China's north-east have cracked down with dawn raids on neighbourhoods in search of North Koreans. This week, a barbed-wire fence was going up along the border. China is taking no risks.