The following is background from the April 11, 2003 CQ Researcher issue entitled "North Korean Crisis" by Mary Cooper:
North Korea emerged from the ashes of World War II in 1945 to become one of the most enduring vestiges of the Cold War. But the culture and political ideology of the communist state are unique, owing as much to the Korean Peninsula's troubled history as to Cold War rivalry. Indeed, the authoritarian, paternalistic, isolationist and highly militaristic regime that rules North Korea today has its roots in Korea's troubled dealings over the millennia with its powerful neighbors — China, Russia and Japan. 
For many years, Korea managed to ward off Western encroachment, which began in earnest with U.S. Navy Commodore Matthew C. Perry's opening of Japan to foreign trade in the mid-19th century. Indeed, Americans' first attempt to penetrate Korea's isolation ended badly. In 1866, when the U.S.S. General Sherman steamed up the Taedong River to the outskirts of Pyongyang, local inhabitants burned the ship and killed all its crew. North Korea's late leader, Kim Il Sung, claimed that his great-grandfather participated in that attack, now celebrated as a heroic victory against foreign invaders.
Korea's isolation was short-lived. Japan annexed the peninsula in 1910 and turned it into a colony whose natural resources would help build the Japanese war machine. Korea's occupiers industrialized the peninsula, building factories, roads and hydroelectric dams and laying the foundations of later private industrial development in the south and state-controlled industry in the north.
The colonial experience, which ended with Japan's defeat in World War II, left a lasting impression of national humiliation that would feed Korean aspirations for independence.
Korean resentment of its colonial status fueled intermittent protests and insurrections that were brutally suppressed by Japanese administrators. Exiled to China and the Soviet Union, some of the dissidents, including Kim Il Sung, gained military training. After Japan annexed Manchuria in 1931, the rebel leaders returned to the region and led guerrilla actions against the Japanese occupation forces, which had a profound influence on North Korea's military and ideological development. Indeed, Kim and his resistance compatriots would occupy most leadership positions in North Korea for the next 50 years.
Even before World War II ended, the United States and its allies began deliberating the future of Korea. At a meeting in Cairo, Egypt, in December 1943, they endorsed President Franklin D. Roosevelt's vague proposition that upon Japan's defeat Korea would become independent “in due course.” The Roosevelt administration also reversed traditional American non-involvement in Korean affairs by defining security on the peninsula as important to postwar Pacific — and therefore U.S. — security.
On Aug. 11, 1945, War Department officials, without consulting Korean or Soviet officials, made the fateful decision to divide Korea into Soviet and U.S. zones separated along the 38th parallel. In early September, 25,000 American soldiers occupied southern Korea, ending the hated Japanese occupation of the peninsula. But they immediately faced opposition among Koreans who saw the U.S. presence as a continuation of colonialism and resented the notion that they were not ready for independence. Meanwhile, Soviet forces occupied Korea north of the 38th parallel and brought with them Kim Il Sung and other communist leaders who had left the country during the Japanese occupation.
Soviet leader Josef Stalin had quietly accepted the partition of Korea, but U.S.-Soviet relations quickly chilled. Although Korea was home to one of the oldest communist movements in Asia, the United States saw the emergence of communist leanings in the South in late 1945 as evidence of a Soviet plan to dominate the entire peninsula.
In 1947, President Harry S Truman called for the containment of communism within existing boundaries — the so-called Truman Doctrine. The U.S. won United Nations support for U.N.-supervised elections for all of Korea if the Soviet Union approved the plan. When it didn't, elections were held in the South in May 1948, resulting in the establishment of the Republic of Korea and the ascendance to power of Syngman Rhee, the first of several authoritarian leaders who would rule South Korea for the next three decades. 
Kim, meanwhile, had emerged as the leader of the communist movement that consolidated power in the North and established a central government in February 1946. Over the next year, land and industries were nationalized and brought under a system of central planning along the Soviet model. Bolstered by his earlier activities as a nationalist guerrilla, Kim became highly popular, far more than the new leaders in the South, who were regarded by many Koreans as puppets of the American colonial occupiers.
Kim strengthened his hold with the merger of communist parties in 1949 into the Korean Workers' Party, which dominated the new Democratic People's Republic of Korea (DPRK) from its founding on Sept. 9, 1948, three weeks after the Republic of Korea's formation.
In contrast to Soviet-supported regimes in Eastern Europe, Kim's brand of communism was no mere copy of the Soviet model — partly because of Stalin's withdrawal of Soviet forces from Korea in 1948. Kim infused a singularly Korean theme into his communist system through the adoption of chuch'e ideology. Defined roughly as keeping foreigners at arm's length, chuch'e appealed to the traditional Korean ideals of self-reliance and independence. Kim put his doctrine into action in 1955, when he distanced his regime from the Soviet Union, and throughout his rule by subjecting North Koreans to continual political indoctrination.
In 1949, Kim had himself named suryng, an old Korean word for “leader” that was modified to mean “great leader.” That year he began condemning South Korea as a puppet state.
Although neither Seoul nor Pyongyang recognized the 38th parallel as a legitimate boundary, historians generally blame the North — and not the South — for the outbreak of the Korean War. Bolstered by some 100,000 war-trained forces and support from China and, to a lesser degree, the Soviet Union, North Korean forces invaded South Korea on June 25, 1950, and took control of all but a small corner of southeastern Korea around the port city of Pusan.
In September, U.N. and South Korean forces led by U.S. Gen. Douglas MacArthur drove out the invaders. The war dragged on for another three years, costing the lives of some 800,000 Koreans on both sides of the parallel, 115,000 Chinese and 37,000 Americans and laying waste to much of the peninsula. An armistice was signed in the summer of 1953 recognizing the de facto division of Korea.
The war's conclusion 50 years ago this July 27, 2003 came not with a peace treaty but with an armistice that merely suspended the hostilities and separated the two sides at the 38th parallel. To bolster South Korea's military forces, the United States retained a sizable military presence in South Korea, backed by naval forces in the Pacific and, ultimately, its superpower nuclear deterrent. Faced with such a formidable adversary, North Korea poured its resources into creating one of the most militarized societies on Earth — eventually building a million-man army equipped with some 11,000 artillery pieces.
It was not long before the North sought to move beyond its conventional arsenal. As early as 1964, Pyongyang set up a nuclear-energy research complex at Yongbyon, where the Soviets built Korea's first nuclear reactor a year later. A plutonium-reprocessing plant and other support facilities appeared over the next two decades.
Despite signing the NPT in 1985 — which barred signatories without nuclear weapons from developing them — barely two years later Pyongyang began hindering U.N. inspections of its nuclear facilities to ensure compliance with the treaty. The IAEA inspectors did not gain access to North Korean nuclear facilities until May 1992. Amid intelligence reports that North Korea was secretly continuing its nuclear program at clandestine sites, their findings were inconclusive.
Besides pursuing a nuclear capability, North Korea also is believed to have developed biological and chemical weapons beginning in the early 1980s, even though in 1987 it acceded to the 1972 Biological and Toxin Weapons Convention banning pathogens for military uses. But, according to the Washington-based Nuclear Threat Initiative, North Korea produced weapons containing anthrax, botulinum toxin and plague. 
The group also estimates that North Korea has 12 chemical-weapons plants producing some 4,500 tons of mustard, phosgene, sarin and other chemicals — and that annual production could reach 12,000 tons in case of war. Unlike the United States, North Korea never signed the 1993 Chemical Weapons Convention, which bans chemical weapons and provides for monitoring compliance, including intrusive inspections and allowances for sanctions and the use of force against violators. In addition, North Korea's thousands of artillery systems can deliver chemical weapons into the DMZ and Seoul. 
Since the 1970s, military experts say North Korea has been developing missiles capable of reaching targets beyond the range of conventional artillery. By 1984, it had tested a ballistic missile based on the Soviet Scud technology, and it has since produced several types of missiles, including 100 of the advanced, 800-mile-range Nodong. The even longer-range Taepodong-1 failed during a 1998 test launch, while the newer Taepodong-2, which potentially could reach the U.S. West Coast, is reportedly almost ready for testing.
Although there is no evidence that North Korea has exported its weapons of mass destruction, it has sold its missile technology to several countries, including Egypt, Iran, Libya, Pakistan, Syria and Yemen.
 Unless otherwise noted, material in this section is based on “North Korea — A Country Study,” Library of Congress, June 1993.
 For more information on Korea's postwar history, see Selig S. Harrison, Korean Endgame (2002).
 “North Korea Overview,” Nuclear Threat Initiative, January 2003.
 For background, see Mary H. Cooper, “Chemical and Biological Weapons,” The CQ Researcher, Jan. 31, 1997, pp. 73-96.