Korean War (1950–1953)

In South Korea, the war is usually referred to simply as "6-25", referring to the date of the outbreak (as with the 9/11 designation for the 2001 terrorist attack on the World Trade Center in New York). Less commonly, one finds the formal designation "Korean War" (Hanguk jeonjaeng 한국 전쟁 / 韓國戰爭).

In North Korea, it is officially called the "Fatherland Liberation War" (Joguk haebang Jŏnjaeng 조국해방전쟁).

In China, it was officially called the "War to Resist the United States and Aid Korea" (Chinese 抗美援朝戰爭 / 抗美援朝战争, Pinyin Kàngměiyuáncháo zhànzhēng), today often simply "Korean War" (Chinese 朝鮮戰爭 / 朝鲜战争, Pinyin Cháoxiǎn zhànzhēng).

In the USA it was officially called only Korean Conflict and declared as a police action, mainly to avoid a declaration of war. Nevertheless, the term Korean War is also in common use there.

Often referred to as the "forgotten war", the Korean War is one of the great conflicts of the 20th century, but is relatively rarely mentioned.

From 1894, the Empire of Korea had come under the domination of the Empire of Japan and was annexed by Japan in 1910. After Japan's surrender in 1945, Korea was not liberated but divided into two occupation zones under the victorious powers. Behind this was above all Great Britain, which feared that in the event of Korean independence the temporarily Japanese-occupied British colonies might also make similar demands.

The Soviet Union occupied the area north of the 38th parallel, and the United States of America occupied the southern area. The Allies had decided at the Yalta Conference that Korea should eventually become a unified, independent country under an elected government, but did not specify the details. After the Cold War began, both sides finally refused to carry out this decision. The 38th parallel became the demarcation line.

The UN, which at that time was close to the USA, took over the mandate for reunification on 14 November 1947. The anti-communist US held elections on May 10, 1948 under UN supervision, but due to lack of cooperation from the Soviet Union, only in the South. Rhee Syng-man, who had returned from exile in the USA, emerged as the winner. Rhee Syng-man came from the Joseon dynasty of Korea, deposed by the Japanese in 1910, and was an early representative of the nationalist resistance against the Japanese. Some observers called the election unfair or rigged. Rhee Syng-man took over the reins of government from the United States on August 13, 1948, and proclaimed the Republic of Korea on August 15. In response, the Soviet-sponsored Kim Il-sung proclaimed the Democratic People's Republic of Korea on September 9. Kim Il-sung was a dictator by Western standards, but the pro-American and anti-communist Rhee Syng-man also showed clear autocratic tendencies.

The US saw the socialist states of the time as a bloc led by the Soviet Union and assumed that North Korea was seeking war as its pawn. This was also the decisive reason for the great American involvement. Today, on the basis of Russia's opened archives, on the other hand, Kim Il-sung in particular is seen as the driving force who pushed the reluctant Joseph Stalin to take the risk of a confrontation with the United States - not least by also playing Stalin off against Mao. Both the Democratic People's Republic of Korea and the Republic of Korea saw themselves as representing the whole country and wanted to unify it under their respective systems. Both sides were ruthless in their approach to resistance and sought escalation, often resulting in skirmishes at the demarcation line before the war.

In early 1949, Kim Il-sung tried to convince Stalin that the time had come for a conventional invasion of the South. Stalin refused, however, because the North Korean troops were still quite poorly trained and he feared U.S. interference. Over the next year, the North Korean army was formed into an offensive organization modeled on the Soviet army and equipped with weapons from the Soviet Union. The Soviet Union simultaneously withdrew its troops from Korea in order to diplomatically coerce the United States to follow suit. By early 1950, however, North Korea was clearly superior to the South in every weapon category, which is why Washington hesitated.

On January 12, 1950, U.S. Secretary of State Dean Acheson told the National Press Club that the U.S. defensive perimeter ran from the Aleutians to Japan to the Ryūkyū Islands to the Philippines. By this "defensive perimeter" he seemed to be indirectly stating that the US would not fight for Korea. This probably ill-advised remark encouraged North Korea to seek conflict. During a March/April 1950 visit by Kim to Moscow, Stalin authorized the invasion.