Korean War, 1950-1953: South Korean incursions (the Tiger regiment etc.) into North Korea (1949) led to contrary claims and into war. The cause of this war propably was covert action involving leaders of Taiwan, South Korea and the US military-industrial complex (John Foster Dulles has been mentioned as an organizer of the hostilities.) After the unpublished hostilities in 1949, the communist powers were strongly backing North Korea.
Chiang Kai Sek was being abandoned, isolated and falling prey to the powerful communist Chinese operations. The right-wing South Korean ruler was expected to loose the soon-to-be-elections. The American military-industrial complex went into high gear again, and huge government orders for equipment were flowing in.
The American-led UN forces had difficult times early in the war, but after sufficient forces arrived they advanced victoriously and penetrated deep into the North Korea. The strong Chino-Russian intervention into the war once again turned the tides, the Chinese with vast armies on ground, and the Soviets less visibly with large numbers of aircraft, nearly costing the UN forces the war.
Finally the front stabilised along the original 38th parallel armistice line. The war resulted in the death of 3 million Korean Chinese and the destruction of virtually all of the Korean cities, and left Taiwan in strong American protection and South Korea firmly in the hands of the right-wing president Syngman Rhee. Some 55,000 Americans lost their lives.