Kim Jong Un’s regime would certainly struggle to survive without its biggest benefactor, China, which accounts for more than 90% of foreign trade, including food and fuel.
That was not always the case. In the early 1960s it was the Chinese who fled famine across the Tumen river. Some even went to school in North Korea because they believed its education system at the time was better.
The North Korean economy crashed after the fall of the Soviet Union in 1991 – which had been its main source of aid and cheap oil – sparking severe food shortages and, eventually, famine.
Soon, North Korean refugees began wading through an often freezing river at the risk of being shot dead to escape hunger, poverty and repression. There are now more than 30,000 of them in South Korea and an unknown number still live in China.
“Since the collapse of the Soviet Union, North Korea hasn’t really had any choice but to maintain good relations with China, which has been its sole benefactor,” Mr Green says.
But now, he adds, Russia “is offering an alternative and the North Koreans are seeking to exploit that”.
Mao Zedong, the first leader of the People’s Republic of China, had likened the relationship between Beijing and Pyongyang to the closeness between “lips and teeth”: “If the lips are gone, the teeth will be cold.”