when did un troops approach the yalu river
Yalu River The Korean side of the river was heavily industrialized during the period of Japanese rule (1910–1945), and by 1945 almost 20% of Imperial Japan's total industrial output originated in Korea. During the Korean War, the movement of United Nations troops approaching the river precipitated massive Chinese intervention from around Dandong. In the course of the conflict every bridge across the river except one was destroyed. The one remaining bridge was the Sino–Korean Friendship Bridge connecting Sinuiju, North Korea to Dandong, China. During the war the valley surrounding the western end of the river also became the focal point of a series of dogfights for air superiority over North Korea, earning the nickname "MiG Alley" in reference to the MiG-15 fighters flown by the combined North Korean, Chinese and Soviet forces.[citation needed]
Lena River Originating at an elevation of 1,640 meters (5,381 ft) at its source in the Baikal Mountains south of the Central Siberian Plateau, 7 kilometres (4 mi) west of Lake Baikal, the Lena flows northeast, being joined by the Kirenga River, Vitim River and Olyokma River. From Yakutsk it enters the lowlands and flows north until joined by its right-hand tributary the Aldan River and its most important left-hand tributary, the Vilyuy River. After that, it bends westward, flowing alongside the Verkhoyansk Range and then making its way nearly due north to the Laptev Sea, a division of the Arctic Ocean, emptying south-west of the New Siberian Islands by the Lena Delta – 30,000 square kilometres (11,583 sq mi) in area,[2] and traversed by seven principal branches, the most important being the Bykovsky channel, farthest east.