<Tr> <Td> Official languages </Td> <Td> Korean </Td> <Td> Korean </Td> </Tr> <Tr> <Td> Official script </Td> <Td> Chosŏn'gŭl </Td> <Td> Hangul </Td> </Tr> <P> The Korean peninsula had been occupied by Japan from 1910 . On August 9, 1945, in the closing days of World War Two, the Soviet Union declared war on Japan and advanced into Korea . Though the Soviet declaration of war had been agreed by the Allies at the Yalta Conference, the US government became concerned at the prospect of all of Korea falling under Soviet control . The US government therefore requested Soviet forces halt their advance at the 38th parallel north, leaving the south of the peninsula, including the capital, Seoul, to be occupied by the US . This was incorporated into General Order No. 1 to Japanese forces after the Surrender of Japan on August 15 . On August 24, the Red Army entered Pyongyang and established a military government over Korea north of the parallel . American forces landed in the south on September 8 and established the United States Army Military Government in Korea . </P> <P> The Allies had originally envisaged a joint trusteeship which would steer Korea towards independence, but most Korean nationalists wanted independence immediately . Meanwhile, the wartime co-operation between the Soviet Union and the US deteriorated as the Cold War took hold . Both occupying powers began promoting into positions of authority Koreans aligned with their side of politics and marginalizing their opponents . Many of these emerging political leaders were returning exiles with little popular support . In North Korea, the Soviet Union supported Korean Communists . Kim Il - sung, who from 1941 had served in the Soviet Army, became the major political figure . Society was centralized and collectivized, following the Soviet model . Politics in the South was more tumultuous, but the strongly anti-Communist Syngman Rhee emerged as the most prominent politician . </P>

What led to the deterioration of relations between north and south korea
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