In the 1960s and 1970s many thousands of people fled Vietnam, Laos and Cambodia. Countries like Thailand may not have welcomed the refugees with open arms, but they did let them stay. In the late 1980s Thailand also allowed tens of thousands of Burmese refugees to set up more or less permanent camps along the border. That relatively humane policy seems to have vanished. The deportation last month of 4000 Hmong refugees from Thailand back to Laos is part of a broader story. Cambodia recently sent a group of Uighurs back to China, where they are almost sure to face trial, torture and long prison terms.

Obama’s foreign policy rests on the idea that the world has entered an era in which major powers can work together on such issues as climate change and trade, and that nations can always find some common ground. Arriving in Tokyo, the president emphasised his shared roots with many Asians, and suggested that a new era of co-operation in the region is around the corner. ‘I am an American president who was born in Hawaii and lived in Indonesia as a boy,’ Obama said, calling himself ‘America’s first Pacific president’. But across Asia, that common ground will be hard to find.