The Korean War was ignited by the 1950 invasion of South Korea when the North Korean Army moved south on June 25, 1950 to attempt to reunite the Korean peninsula, which had been formally divided since 1948. The conflict was then expanded by the United States, China's and the Soviet Union's involvement. The main hostilities were during the period from June 25, 1950, until the Korean Armistice Agreement was signed on July 27, 1953.