BEIJING -- North Korean "refugees," economic migrants or defectors -- take your pick -- in China have been in the news again. Staged video film of dozens of them storming embassies in Beijing has been circulated globally by South Korean and Western political activists who arrange for these incidents.

The border between China and North Korea runs for about 1,600 km along two rivers, from Dandong on the Yalu River in Liaoning province to Hunchun on the Tumen River in Jilin province.

China and North Korea are allies. There are no fortifications along either side of the rivers, no fences, no patrols on the river apart from areas close to the 11 bridges (built by Japan when it occupied Manchuria and Korea), and no visible signs of army or police except in the vicinity of the bridges.