North Korea vs. China

risking arrest, imprisonment, and deportation, tens of thousands of North Koreans cross into China to escape famine, economic privation, and political oppression; North Korea and China dispute the sovereignty of certain islands in Yalu and Tumen Rivers; Military Demarcation Line within the 4-km-wide Demilitarized Zone has separated North from South Korea since 1953; periodic incidents in the Yellow Sea with South Korea which claims the Northern Limiting Line as a maritime boundary; North Korea supports South Korea in rejecting Japan's claim to Liancourt Rocks (Tok-do/Take-shima)

China and India continue their security and foreign policy dialogue started in 2005 related to a number of boundary disputes across the 2,000 mile shared border; India does not recognize Pakistan's 1964 ceding to China of the Aksai Chin, a territory designated as part of the princely state of Kashmir by the British Survey of India in 1865; China claims most of the Indian state Arunachal Pradesh to the base of the Himalayas, but the US recognizes the state of Arunachal Pradesh as Indian territory; Bhutan and China continue negotiations to establish a common boundary alignment to resolve territorial disputes arising from substantial cartographic discrepancies, the most contentious of which lie in Bhutan's west along China's Chumbi salient; Chinese maps show an international boundary symbol (the so-called "nine-dash line") off the coasts of the littoral states of the South China Sea, where China has interrupted Vietnamese hydrocarbon exploration; China asserts sovereignty over Scarborough Reef along with the Philippines and Taiwan, and over the Spratly Islands together with Malaysia, the Philippines, Taiwan, Vietnam, and Brunei; the 2002 Declaration on the Conduct of Parties in the South China Sea eased tensions in the Spratlys, and in 2017 China and ASEAN began confidential negotiations for an updated Code of Conduct for the South China Sea designed not to settle territorial disputes but establish rules and norms in the region; this still is not the legally binding code of conduct sought by some parties; Vietnam and China continue to expand construction of facilities in the Spratlys and in early 2018 China began deploying advanced military systems to disputed Spratly outposts; China occupies some of the Paracel Islands also claimed by Vietnam and Taiwan; the Japanese-administered Senkaku Islands are also claimed by China and Taiwan; certain islands in the Yalu and Tumen Rivers are in dispute with North Korea; North Korea and China seek to stem illegal migration to China by North Koreans, fleeing privation and oppression; China and Russia have demarcated the once disputed islands at the Amur and Ussuri confluence and in the Argun River in accordance with their 2004 Agreement; China and Tajikistan have begun demarcating the revised boundary agreed to in the delimitation of 2002; the decade-long demarcation of the China-Vietnam land boundary was completed in 2009; citing environmental, cultural, and social concerns, China has reconsidered construction of 13 dams on the Salween River, but energy-starved Burma, with backing from Thailand, continues to consider building five hydro-electric dams downstream despite regional and international protests