What's a poor North Korean refugee in China to do? Staying put, you have to hide out. Other than lie low, or return to North Korea, there are two options. One is to seek asylum in a foreign mission in China. Some years ago there was a rush of embassy incursions in Beijing, aided by activists. The lucky ones who made it eventually got to Seoul; but since then security around embassies has been tightened.
A few still succeed via this diplomatic route, but for most, the only option is to continue the journey: to get out of China into another country.
That means going either north or south: to Mongolia, or Southeast Asia. Either journey is both physically arduous and risky. A 17-year-old boy, Lee Chol-hun, who had spent half his life hiding in China, was shot - in the back, by some accounts - and killed by a Chinese border guard while trying to cross into Mongolia.
Even once over the border, the unforgiving Gobi takes its toll. Yoo Chul-min was just 10 when he perished, lost and exhausted in the desert.
The southerly route, which more take, has its own perils. You have to cross the length of China. Physically you blend in, but just hope no one tries to talk to you and twigs that you're a foreigner. Again this is costly and risky. An "underground railway" of activist NGOs may help with money and safe houses.
--Aidan Foster-Carter, honorary senior research fellow in sociology and modern Korea, Leeds University, England.