Yalu (yäˈlōˈ) [key], Korean Amnok, river, c.500 mi (800 km) long, rising in the Changbai Mts. in Jilin prov., NE China, and flowing SW to the Bay of Korea at Dandong; forms part of the China–North Korea border. In places it is navigable for shallow-draft vessels, but its chief commercial use is for floating timber to sawmills. Several railroad bridges span the river. The Supung Dam above Sinuiju, North Korea, one of the largest dams in Asia, supplies hydroelectric power to China and North Korea. Chinese troops entered the Korean War by crossing the Yalu.