The Soviet Union recognized Kim's regime as having sovereignty over the whole Korea, including the south. It is generally accepted that Kim invaded the south by his own decision and that the Soviets did not influence him. The south was caught completely by surprise when Kim's army invade in the early morning of June 25, 1950. The KPA captured Seoul and most of the south apart from Pusan in the south-east. UN forces backed mostly by the United States landed in Korea and began to push the KPA back north. Firstly, the UN forces managed to push the KPA back behind the 38th parallel (the imaginary line that divided the Koreas during the war). The newly formed People's Republic of China was at first reluctant to the idea that the Koreas would be reunited under Kim's regime but accepted when Kim told them that Stalin approved the invasion.