Korean War

Communist nation North Korea invaded the peaceful nation of South Korea

This war was the result of communism from the communist nation of china during the cold war and Chinese civil war.
On Saturday, 24 June 1950, U.S. Secretary of State Dean Acheson informed President Truman that the North Koreans had invaded South Korea.^[125][126] Truman and Acheson discussed a U.S. invasion response and agreed that the United States was obligated to act, paralleling the North Korean invasion with Adolf Hitler's aggressions in the 1930s, with the conclusion being that the mistake of appeasement must not be repeated.^[127] Several U.S. industries were mobilized to supply materials, labor, capital, production facilities, and other services necessary to support the military objectives of the Korean War.^[128] However, President Truman later acknowledged that he believed fighting the invasion was essential to the American goal of the global containment of communism as outlined in the National Security Council Report 68 (NSC-68) (declassified in 1975):

Communism was acting in Korea, just as Hitler, Mussolini and the Japanese had ten, fifteen, and twenty years earlier. I felt certain that if South Korea was allowed to fall, Communist leaders would be emboldened to override nations closer to our own shores. If the Communists were permitted to force their way into the Republic of Korea without opposition from the free world, no small nation would have the courage to resist threat and aggression by stronger Communist neighbors.^[129]

In the resulting Battle of Pusan Perimeter (August–September 1950), the U.S. Army withstood KPA attacks meant to capture the city at the Naktong Bulge, P'ohang-dong, and Taegu. The United States Air Force (USAF) interrupted KPA logistics with 40 daily ground support sorties that destroyed 32 bridges, halting most daytime road and rail traffic. KPA forces were forced to hide in tunnels by day and move only at night.^[144] To deny matériel to the KPA, the USAF destroyed logistics depots, petroleum refineries, and harbors, while the U.S. Navy air forces attacked transport hubs. Consequently, the over-extended KPA could not be supplied throughout the south.^[145]
Meanwhile, U.S. garrisons in Japan continually dispatched soldiers and matériel to reinforce defenders in the Pusan Perimeter.^[146] Tank battalions deployed to Korea directly from the U.S. mainland from the port of San Francisco to the port of Pusan, the largest Korean port. By late August, the Pusan Perimeter had some 500 medium tanks battle-ready.^[147] In early September 1950, ROK Army and UN Command forces outnumbered the KPA 180,000 to 100,000 soldiers. The UN forces, once prepared, counterattacked and broke out of the Pusan Perimeter.^[43

By mid-1950, North Korean forces numbered between 150,000 and 200,000 troops, organized into 10 infantry divisions, one tank division, and one air force division, with 210 fighter planes and 280 tanks, who captured scheduled objectives and territory, among them Kaesong, Chuncheon, Uijeongbu, and Ongjin. Their forces included 274 T-34-85 tanks, some 150 Yak fighters, 110 attack bombers, 200 artillery pieces, 78 Yak trainers, and 35 reconnaissance aircraft.^[55] In addition to the invasion force, the North KPA had 114 fighters, 78 bombers, 105 T-34-85 tanks, and some 30,000 soldiers stationed in reserve in North Korea.^[55] Although each navy consisted of only several small warships, the North and South Korean navies fought in the war as sea-borne artillery for their in-country armies.
In contrast, the ROK Army defenders were relatively unprepared and ill-equipped. In South to the Naktong, North to the Yalu (1961), R.E. Appleman reports the ROK forces' low combat readiness as of 25 June 1950. The ROK Army had 98,000 soldiers (65,000 combat, 33,000 support), no tanks (they had been requested from the U.S. military, but requests were denied), and a 22-piece air force comprising 12 liaison-type and 10 AT6 advanced-trainer airplanes. There were no large foreign military garrisons in Korea at the time of the invasion, but there were large U.S. garrisons and air forces in Japan.^[55]
Within days of the invasion, masses of ROK Army soldiers—of dubious loyalty to the Syngman Rhee regime—were either retreating southwards or were defecting en masse to the northern side, the KPA.^[46