Korea was ruled by Japan from 1910 until the end of the war. American authorities divided the Korean peninsula along the 38th Parallel with the U.S. military occupying the southern half and the Soviet forces in the northern half. After the failure to hold elections in 1948 on the Korean Peninsula, the growing hostility between the Soviets and the Americans was reflected in the growing hostility between North Korea with its communist government and South Korea with a right-wing government. In 1950, the North invaded the South and started the Korean War. The United Nations sent a multination force to support the South and the Peoples Republic of China came in to support the North. The war was hard fought with many casualties on both sides. It ended in 1953 with an armistice agreement that restored the 38th Parallel as the border between the North and the South and created the two and one half miles Korean Demilitarized Zone between the two states.
While South Korea became an economic engine that raised the standard of living of its citizens, North Korea descended into a poverty-stricken belligerent dynastic totalitarian state. There have been repeated violations of the DMZ by the North over the years. The North Koreans maintain one of the largest armies on earth at the expense of their civilian population and repeatedly threaten to invade the South. The U.S. maintains troops in South Korea near the DMZ to counter the North Korean treat. This confused and dangerous situation has continued for sixty years.
The North Koreans began serious research in nuclear physics and technology with the help of the Soviet Union a few years after the end of the Korean War. The United States deployed nuclear warheads in South Korea in 1958 which increased North Korean paranoia. The North Korean Yongbyon Nuclear Scientific Research Center (YNSRC) was opened in 1963. In 1965, the Soviets supplied the North Koreans with a IRT-2000 pool research reactor for the YNSRC. In the late 1970s, North Korea began mining uranium. In the Early 1980s, the North Koreans built a factory at the YNSRC to create nuclear fuel from the yellowcake produced by their mines. A reprocessing plant was completed at the YNSRC in 1984 for the purpose of recovering plutonium from spent nuclear fuel. Also completed around 1985 was a gas-cooled graphite reactor that the U.S. decided was intended for plutonium production.
With the fall of the Soviet Union around 1990, the North Koreans lost their main benefactor and protector. Satellite photos convinced the U.S. that North Korea had embarked on construction of new nuclear facilities at the YNSRC. Although North Korea had signed the Nuclear Non-proliferation Treaty, they did not permit inspection of their nuclear facilities. The U.S. and other nations were concerned that North Korea was actively pursuing the construction of nuclear weapons. In spite of this, the U.S. withdrew its last nuclear warhead from South Korea in 1991.
Experimental IRT-2000 reactor at Yongbyon:
