Question: Who led North Korea in to the war where UN troops approached the Yalu river.

Knowledge 1: 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. [SEP] Knowledge 2: North Korea
North Korea (Korean: ; MR: "Chosŏn" or literally ; MR: "Pukchosŏn"), officially the Democratic People's Republic of Korea (DPRK or DPR Korea; Korean: , "Chosŏn Minjujuŭi Inmin Konghwaguk"), is a country in East Asia constituting the northern part of the Korean Peninsula, with Pyongyang the capital and the largest city in the country. To the north and northwest, the country is bordered by China and by Russia along the Amnok (known as the Yalu in Chinese) and Tumen rivers and to the south it is bordered by South Korea, with the heavily fortified Korean Demilitarized Zone (DMZ) separating the two. Nevertheless, North Korea, like its southern counterpart, claims to be the legitimate government of the entire peninsula and adjacent islands.
Knowledge 1: 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. [SEP] Knowledge 2: United States in the Korean War
In response to North Korea's invasion into South Korea the United Nations convened to formulate a response. The U.N. demanded North Korea's immediate withdrawal and, when this was not met, United States Army General Douglas MacArthur was appointed supreme commander of U.N. forces. To halt the rapid progress of North Korean forces into the south Task Force Smith was deployed to the Korean front from Japan. Task Force Smith consisted of U.S. Army officers and regiments of the Army's 24th Infantry Division that were stationed in Japan as occupational forces. Unfortunately the 24th were under trained, poorly supplied, and outnumbered. The 24th offered very little resistance against the North Korean advance. American and South Korean troops were pushed south and in late July 1950 Task Force Smith was overrun in the city of Taejon. Troops from the Army's 25th Infantry Division were deployed to Taejon to establish a new line and pullout the decimated 24th I.D. This addition of combat troops did not stop the North Korean advance and both American and South Korean troops were pushed further south.
Knowledge 1: 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. [SEP] Knowledge 2: Korean War
After the first two months of the conflict, South Korean forces were on the point of defeat, forced back to the Pusan Perimeter. In September 1950, an amphibious UN counter-offensive was launched at Inchon, and cut off many of the North Korean attackers. Those that escaped envelopment and capture were rapidly forced back north all the way to the border with China at the Yalu River, or into the mountainous interior. At this point, in October 1950, Chinese forces crossed the Yalu and entered the war. Chinese intervention triggered a retreat of UN forces which continued until mid-1951. After these dramatic reversals of fortune, which saw Seoul change hands four times, the last two years of conflict became a war of attrition, with the front line close to the 38th parallel. The war in the air, however, was never a stalemate. North Korea was subject to a massive bombing campaign. Jet fighters confronted each other in air-to-air combat for the first time in history, and Soviet pilots covertly flew in defense of their Communist allies.

Answer: Kim Il - Sung