Korea was split in two at the end of the Second World War, when the Soviet Union occupied the north of the peninsula and the United States the south, with the 38th parallel as the boundary. Meant as a temporary arrangement, the line hardened as the two powers fell out, and in 1948 two rival states were founded: South Korea and North Korea. The Korean War of 1950 to 1953 ended without reuniting them, and the peninsula remains divided.
Wartime plans
Korea had been a Japanese colony since the Japan–Korea Treaty of 1910. At Cairo in November 1943 Roosevelt, Churchill and Chiang Kai-shek declared that Korea should in due course become free and independent. Roosevelt proposed a period of international trusteeship first and raised it with Stalin at Tehran and again at the Yalta Conference in February 1945, and the Soviet leader raised no objection, asking only that it be brief.
A line on a map
The Soviet Union declared war on Japan on 8 August 1945, and its troops moved quickly into northern Korea. Worried that they might occupy the whole country, Washington on 10 August gave two junior officers, Dean Rusk and Charles Bonesteel, the job of drawing an American zone. Working at short notice from a National Geographic map and without consulting anyone who knew Korea, they chose the 38th parallel because it divided the country roughly in half while leaving the capital, Seoul, on the American side. Rusk later said that had he known Korea's history he would almost certainly have chosen another line. To American surprise, Moscow accepted at once, and the division was written into General Order No. 1 for the surrender of Japan. The line left roughly sixteen million Koreans under American occupation and nine million under Soviet.
Two occupations
Soviet troops held most northern cities by 24 August and worked through local people's committees, while also bringing in Korean communists from the Soviet Union. They promoted Kim Il Sung, who in February 1946 headed a provisional government that soon carried out a sweeping land reform; according to the American military government, some 400,000 northerners fled south. The Americans under General John R. Hodge landed at Incheon on 8 September 1945 and set up a military government. Hodge declined to meet envoys of the exiled Korean Provisional Government and refused to recognise the People's Republic of Korea, proclaimed by a congress in Seoul two days before he landed, outlawing it that December. The south was troubled by inflation, a large uprising in 1946 and left-wing insurgencies.
Failure of trusteeship
In December 1945 the Allies agreed at Moscow on a trusteeship of up to five years by four powers. Many Koreans opposed it, and a joint US–Soviet commission meeting in 1946 and 1947 made no progress as relations between the superpowers worsened. From May 1946 crossing the parallel without a permit was illegal. In September 1947 the United States took the question to the United Nations, which called for elections across Korea; the Soviet Union rejected the UN's role, and the vote went ahead in the south alone.
Two states
Separate elections were widely unpopular. On the island of Jeju an uprising against them began in April 1948, and its suppression killed between 25,000 and 30,000 people. The southern election of 10 May 1948 took place amid violence and a boycott by many of Syngman Rhee's opponents. The Republic of Korea was proclaimed in Seoul on 15 August 1948 with Rhee as president, and the Democratic People's Republic of Korea followed in Pyongyang on 9 September, with Kim Il Sung as premier. Each claimed the whole peninsula. Soviet troops left in December 1948 and American troops by 1949.
War and armistice
After repeated border clashes, North Korea invaded the South on 25 June 1950. The armistice of 1953 replaced the parallel with a demilitarised zone about four kilometres wide following the front line, which crosses the 38th parallel diagonally. Despite occasional talks, such as the 2018 Panmunjom Declaration, the division has persisted, and in 2024 North Korea amended its constitution to drop references to reunification.
On our maps
Our 1938 map shows Korea under Japanese rule, while the 1945 and 1960 maps show the peninsula divided between North and South.