author of `` Meltdown : The Inside Story of the North Korean Nuclear Crisis . '' `` If that 's what they did , however , it was extremely foolhardy and really pushing their luck . '' China and North Korea share a 1,415-kilometer -LRB- 880-mile -RRB- border that mainly follows two rivers . The Yalu River defines the border on the northwest , the Tumen River on the northeast . By land , the two countries are linked by seven road crossings and four railway points . Over the years , I have visited three towns on the Chinese side of the border . From a narrow river crossing at the border town of Tumen , Koreans cross on foot and in trucks . Those going back into North Korea carry bags full of food and household wares , even bicycles . Some of those coming into China ferry logs and minerals . From across the Yalu River in China 's Dandong City in October of 2006 , I had a glimpse of Sinuiju , a North Korean border town of some 350,000 people . Using a long camera lens , I saw school children learn to roller skate
BEIJING , China -LRB- CNN -RRB- -- North Korea , formally called the Democratic People 's Republic of Korea , is also known as the Hermit Kingdom for a good reason . Chinese border guards patrol in Jilin province across from the North Korean border on March 21 , 2009 . For decades , it has been shrouded by a veil of secrecy that has prevented us from better understanding this important nation . As journalists we seek out the realities of life there , beyond the myths and hype , but that is difficult because the DPRK is generally inaccessible to journalists . The gap between reality and illusion remains profound . Journalists , such as the two Americans being detained in North Korea , do travel to the border between China and North Korea to get a sense of what life is like in the isolated nation of 22 million people . The circumstances surrounding the journalists ' arrest are still unclear . `` North Korea is such a difficult country to enter for a foreign reporter that the temptation to slip across the frozen river border is considerable , '' said former CNN correspondent Mike Chinoy ,