Fifty years after the conflict that killed millions, the Korean peninsula theoretically remains at war.

China had warned that it would repay past debts to Koreans who had fought with them against Chiang Kaishek by defending North Korea against a U.S. invasion. But Washington had ignored the notice.

Two days after the war in Korea began, the U.S., worried that it would "lose" Korea like China to communists, took the matter to the UN Security Council.

On June 25, 1950, the Korean War began. The three years of carnage that ensued would be known as the "Fatherland Liberation War."

North Korea's roots lie deep in Korean history.

To North Korea in 1950, the U.S.-backed Republic of Korea to its south was just the latest installment in Korea's long history of occupation by foreign powers.