The partition was not originally intended to last long, but Cold War politics resulted in the establishment of two separate governments in the two zones in 1948, and rising tensions prevented co-operation. The desire for many Koreans was for a peaceful unification but was dashed when the Korean War broke out in 1950. On 25 June 1950, troops from North Korea invaded South Korea. Mao Zedong encouraged the confrontation with the United States and Joseph Stalin reluctantly supported the invasion. After three years of fighting, which involved both Koreas, China and United Nations forces, the last of which were led by the US, the war ended with an at approximately the same boundary.