Civil War: Korea (1950-1953)

Jung-Yeop Woo. Civil Wars of the World: Major Conflicts since World War II. Editor: Karl DeRouen Jr. & Uk Heo. Volume 2, ABC-CLIO, 2007.

Country Background

The Korean War (1950-1953) resulted from the division of Korea into South Korea and North Korea following the end of World War II in 1945. Immediately following this segregation, efforts to reunify the peninsula were attempted. However, when those efforts ended in failure in 1948, the South declared itself the Republic of Korea (ROK), and the North established the People’s Republic of Korea (DPRK). In 1949, fighting broke out on the border between the two newly created countries. On June 25, 1950, North Korean forces crossed the divide and invaded the South. An armistice was reached in July 1953. To understand the Korean War, we need also to appreciate how the separation of Korea evolved.

Before 1948 and the subdivision into two political entities, the entire Korean peninsula was one unified country ruled by the Chosun Dynasty. Born in 1392 before dying out in 1910, the dynasty’s reign lasted more than half a millennium. In the second half of the nineteenth century, foreign empires sought to increase their influence within the Korean peninsula. Their presence and hopes were met with resistance. South Korea refused to open itself to the world because governing elites, including the king and his immediate subordinates, believed that the society they had achieved through Confucianism needed little or nothing from foreigners outside China. However, when Japan modernized and opened itself to the Western world, to some extent it inspired Korea and influenced Korean politics. In 1876, the Japanese urged Korea to allow diplomatic relations, thereby opening trade between the two countries. This fledgling relationship with Japan weakened Korea’s traditionally close ties to China.

To counter the increasing Japanese influence in Korea, China sought to neutralize its rival by urging Korea to open to the Western countries, which led to the Korea-United States treaty of 1882. But this maneuver failed to slow Japan’s impact and growing power in Asia. Even militarily, the Japanese were becoming the dominant players. In 1895, Japan defeated China in the Sino-Japanese War; ten years later, Japan overcame Russia in the Russo-Japanese War. These victories solidified Japan’s dominant influence on the Korean peninsula: Korea became a Japanese protectorate in 1895 and in 1910 was formally annexed, marking the end of the Chosun Dynasty.

After thirty-five years under harsh Japanese rule, Korea regained its independence on August 15, 1945, after Japan surrendered to the Allies. This surrender, together with the Soviet Union’s landing on the Korean peninsula, would utterly transform Korea. Another important historical incident that shaped Korea’s fate occurred in 1943, at the Cairo Conference. The Allies, including the United States, China, and Britain, agreed to strip Japan of all its territories acquired since 1894. In August 1945, on the eve of the collapse of Japan, the Soviet Union (which had joined the fight against Japan in the northern part of Korea a week earlier) agreed to the U.S. proposal that Korea should be divided into two zones across the thirty-eighth parallel for the purpose of acceptance of military surrender.

The intent was merely to ensure that the Japanese north of the line would surrender to the Soviet Union and those south of the line to the United States. In its declaration of war on Japan, the Soviets agreed to this principle. Yet, no precise formula had been agreed to between Roosevelt and Stalin for governing the newly independent Korea. As Blair (1994) notes, Korea was not much known to the world. No one really knew what to do with it, nor did anyone much care. Consequently, the idea of segregating Korea was chosen hastily and casually. On August 15, 1945, fearing Soviet control of the entire Korean peninsula, U.S. President Harry Truman proposed the division of Korea to Joseph Stalin, who agreed the next day. The thirty-eighth parallel was not intended as a permanent dividing line but was simply a practical solution to the vacuum created in Korea by Japan’s sudden collapse (Chull Baum Kim 1994). As Gupta puts it, in the context of the developing Cold War, “the 38th Parallel turned into a rigid frontier between two Korean client-states under the influence of the United States and the Soviet Union respectively” (Gupta 1972, 701).

Both great powers used their occupational presence to promote governments friendly to their ideologies and interests. The occupation of Korea by the United States and the Soviet Union was arranged without precise definitions of its nature and duration, thereby greatly reducing Korea’s prospects for a smooth transition toward independence and unity (Stueck 1995, 19). The Soviet Union suppressed the moderate nationalists in the north and gave its support to Kim Il Sung, a Communist who had led anti-Japanese guerrillas in Manchuria. In the south, the leftist movement was opposed by various groups of right-wing nationalists. This resistance was due mainly to the U.S. presence, which set up an administration based on the former Japanese colonial structure, in which conservatives held power. Thus, any movements related to socialism or communism were seen as threatening and were suffocated (MacDonald 1996, 47).

The United States found an ally in Syngman Rhee, a nationalist who opposed the Japanese and lived in exile in the United States, and began to support him. During this time, political activity became increasingly polarized between left and right. As Savada and Shaw note, the fate of South Korea was dominated not only by the Cold War antagonism of the two great powers but also by “seemingly irreconcilable political differences among Koreans themselves” (Savada and Shaw 2002, 153).

In May 1948, elections were held in South Korea under the auspices of the United Nations. A national assembly was established according to the outcome of the elections, and this new body elected Syngman Rhee as the first president of the Republic of Korea (South Korea). In the north, a separate regime, the Democratic People’s Republic of Korea (North Korea), led by Kim Il Sung, was established in December. It is necessary to remember that the United Nations declared the South Korean government to be the only lawful government on the Korean peninsula.

Conflict Background

Tension escalated in Korea between the formation of the two Korean states in 1948 and the outbreak of the war in June 1950. Each government, North and South, insisted that it was the only rightful government in Korea. Kaufman (1999) contends that the Korean War was part of a continuing civil conflict in Korea that began with the end of World War II, and not merely an isolated event in history. Thus, the development of the ideological struggle among Koreans must be further understood. This internal battle over ideas, combined with the Cold War atmosphere, provided the basis for the Korean War.

Socialist and revolutionary ideas had become increasingly popular in Korean intellectual circles in the early 1920s owing to the efforts of certain Koreans who had studied and become radicalized in Japan (Hart-Landsberg 1998). Despite Japan’s harsh intervention in and oppression of Korean political life, Communist-inspired resistance continued. Externally, a regional Communist-led resistance movement arose in response to Japanese imperialism in Manchuria and northern China. This continued to influence political consciousness and commitments in Korea. Although Chinese Communists organized and led the main opposition to Japan in Manchuria, Korean Communists also played an important role in the armed struggles there. Some Koreans served as division commanders, Kim Il Sung among them. It was during this conflict that he established his reputation as a liberation fighter in the Second Army. This socialist and Communist movement survived Japan’s harsh oppression. It also strengthened and expanded its network in Korea predominantly by creating close ties with farmers, the working class, and student opposition groups upset with Japanese rule.

However, this growing leftist ideology did not reveal serious social problems until the collapse of Japan became obvious. But when collapse became apparent, clashes broke out between the opposing groups, as worker and peasant unions flourished and Communist strength grew. The conservatives (e.g., landowners, businessmen, and manufacturers) who had enjoyed a privileged status under the Japanese rule sought to retain their status after the liberation. Conversely, political leftists, including large numbers of peasants and workers, sought a radical upheaval in the social and political structure of Korea. This political divide and class struggle provided a base of popular support for the regime in the north and, concurrently, political instability in the south.

During the two years following the establishment of a South Korean government, the domestic political conditions were volatile. The UN General Assembly, influenced by the United States, adopted a resolution in November 1947, hoping to resolve the problem of Korea’s discord by establishing a new national government to govern all of Korea. The resolution recommended that elections be held no later than March 31, 1948. The Soviet Union, however, refused to cooperate with the United Nations. Despite the Soviet balking, the United Nations Temporary Commission on Korea (UNTCOK) was created in 1947 to sponsor and observe the election of a Korean legislative body, which would be authorized to form a Korean government. The United Nations adopted another resolution on February 26, 1948, to proceed with an election in the South. On May 10, 1948, the UN-sponsored general election was held.

Although it faced strong opposition from the Soviet Union, the United States, given its overwhelming influence in the UN, had little trouble winning approval of its motion. UNTCOK’s decision to observe an election in the South alone indicated that their objective was not necessarily a reunification of Korea. Yet, Syngman Rhee and his followers welcomed this resolution, a view not shared by all. In fact, an overwhelming majority of Koreans, including leftists, disputed the election because they feared it would make the separation permanent. Despite the unpopularity of the vote, Syngman Rhee was elected president by the National Assembly on July 20, 1948. U.S. foreign policy had succeeded in dividing Korea and establishing a right-wing government in the South. Yet the violence that continued to spread throughout South Korea undermined the regime’s stability. With support from the North, growing numbers joined guerrilla groups fighting to overthrow the Rhee regime and reunite the country. The guerrilla war in the South began on Jeju Island; it is remembered and referred to as 4.3 because it commenced on April 3, 1948. Discontent with the American occupation and with the troops from the central South Korean regime (still in its early stages of formation under Rhee) precipitated the violent outbreak. The South Korean right-wing government was conducting nationwide campaigns to root out Communists and their sympathizers.

As well as being horrified by this brutality, Jeju residents were also upset with the United Nations, which had abandoned its intent to hold elections that would unify the countries; the election of a South Korean government was to take place in May. Many Koreans saw the elections as merely a smokescreen of legitimacy behind which Rhee would be placed in power and kept beholden to the American occupiers (Thompson 2004). Demonstrations against the election were held on March 1, 1948, and many of the protesters were arrested. On April 3, after brutal treatment by police, the people of Jeju struck back. A guerrilla army of nearly 4,000 took control of most of the villages in Jeju (Hart-Landsberg 1998). The South Korean government sent its military forces to the island to suppress the swelling rebellion. Thompson (2004) reports that estimates of the numbers of civilians killed on Jeju during the 4.3 uprisings range from 10,000 to 80,000 (depending on the agency or reporter). Another rebellion broke out in October 1948, this time in the southern port city of Yosu. South Korean soldiers ordered to quell it refused to fight and even turned against the government.

Although the guerrilla war was being fought in the South, tensions between the North and South states were increasing. When a series of Communist-led rebellions in South Korea were suppressed by the South Korean government, the option of unification by insurgency appeared unviable to the Communists (Rees 1988, 93). So Pyongyang was forced to consider more drastic means of achieving its goal. This explains Macdonald’s contention that “the Korean War should probably be understood as encompassing an era from 1947 to 1955, with the period of 1950-1953 as its hot phase” (MacDonald 1996, 50).

Incidents along the thirty-eighth parallel began to increase. One of the first major battles between the North and the South took place on May 4, 1949. This skirmishing, initiated by the South, lasted four days and left hundreds dead. Another clash occurred in August, when North Korean forces attacked the ROK units. Starting in September 1949, the military balance of power began to shift in favor of North Korea as additional military supplies began to arrive from the Soviet Union and as North Korean troops returned from China (Hart-Landsberg 1998). As their resources grew, so did their boldness; thereafter, the DPRK frequently initiated the fighting.

The Insurgents

The Korean People’s Army of the DPRK crossed the thirty-eighth parallel on June 25, 1950. In the 1970s, however, revisionists began to argue that the war was caused just as much by Western and South Korean provocation (Catchpole 2000, 7). Despite the argument of the revisionists, war-related documents provided by Soviet President Boris Yeltsin in 1994 make it clear that North Korea, operating with major Soviet assistance, was responsible for the invasion (Myers 2001).

Although the Soviet Union and China played an important role in reinforcing the strength of the North Korean People’s Army, it appears that they neither ordered nor encouraged Kim Il Sung to initiate a war in Korea (Gye-Dong Kim 1989, 33). Rather, Kim Il Sung was dedicated to the reunification of Korea and believed that this could only be achieved by the military defeat of the South.

Sources: Korea Institute for Military History Compilation (n.d.); Groningen Growth and Development Centre (n.d.).
War: South Korea vs. North Korea
Dates: June 25, 1950, to July 27, 1953
Casualties (KIA): South Korea: 137,899; North Korea: 520,000; United Nations: 40,670; China: 148,600
Regime type prior to war: South Korea: Republic (presidential system); North Korea: Communist government
Regime type after war: Republic (presidential system)
GDP per capita year war began: US $1,103 in 2002 value for South Korea; no data available for North Korea
GDP per capita 5 years after war: US $1,509 in 2002 value for South Korea; no data available for North Korea
Insurgents: North Korea
Issue: Reunification of Korea, ideological differences
Rebel funding: Support from Soviet Union, China
Role of geography: Not applicable
Role of resources: Not applicable
Immediate outcome: Stalemate, continued partition of Korea
Outcome after 5 years: Hostile relationship
Role of UN: Sent combatants under UNC
Role of regional organization: Not applicable
Refugees: More than 7 million separated families
Prospects for peace: Uncertain in the near future
Table 1: Civil War in Korea

After the Soviet Union agreed to the U.S. proposal—to accept the surrender of remaining Japanese troops north of the thirty-eighth parallel—the Soviets continued to exert influence on the northern part of Korea. Just as the United States did in the South, Soviet forces sought to ensure a political environment in Korea that was favorable to the interests of their country. In this regard, the Soviet occupation favored groups of people strongly inclined to the political left. There were also a number of Korean Communists in the Soviet Far East who were anxious to return to Korea, whose exodus the Soviets encouraged in hopes of building a Communist regime in the North. One of the most famous of these returning Koreans was Kim Il Sung.

There were several differences between U.S. and Soviet policies dealing with the Korean situation at that time. Although the Soviets moved quickly to erase the Japanese presence, the U.S. occupation was based on the structure and personnel of the Japanese colonial government. Although the Soviets supported the work of the Provisional People’s Committee, the U.S. occupation had declared their activities illegal throughout the South. This gained popular support for the North Korean regime, at least during its inception. From the Northern perspective, the United States was deliberately destroying the foundation for Korean unity. The North Korean regime also claimed that it held more legitimacy than the regime in the South. As the North moved ahead with its political reforms, the gap between the two Koreas widened.

The North began to implement its land reform program and to nationalize its major industries and firms. Through this process, the Communists gathered popular support; with support from the Soviet command, they built a formidable political and military structure. They expanded and consolidated their party’s strength in August 1946 by merging all the left-wing groups into the North Korean Workers’ Party. In the same year, the armed forces were organized and reinforced. By June 1950, North Korean troops numbered between 150,000 and 200,000 and were organized into ten infantry divisions, one tank division, and one air force division. Soviet equipment, including automatic weapons of various types, T-34 tanks, and Yak fighter planes, were provided in early 1950.

With this newfound might, Kim Il Sung made plans to invade South Korea. He had been allowed to build such a force because Moscow viewed North Korea as part of a “security blanket” around its borders (Kaufman 1999, 7). In the spring of 1950, Kim visited Moscow and Peking, where he tried to persuade Soviet leader Joseph Stalin and Chinese leader Mao Zedong to approve his plans for an invasion. Both leaders were reluctant; they feared that an attack on South Korea could lead to an American response. Moreover, the Soviet Union was preoccupied with the West, and China did not want to divert its attention from Taiwan.

Today, there exist different views on who was responsible for the Korean War, even though it is now clear who initiated it. But some maintain that Syngman Rhee was also responsible to some extent. His preparations and announcements of a plan to march toward Pyongyang were probably a determining factor in the outbreak of the war because they hastened reinforcement and strengthening of the North Korean People’s Army, as well as advancing the actual invasion date (Gye-Dong Kim 1989, 44). Thus does Gye-Dong Kim (1989) contend that, in fact, both sides in Korea prepared for invasion, although it was the North Koreans who took the initiative.


Although North Korea’s geography did not have strategic importance in the Korean War, an understanding of the land and region is helpful in putting the events in perspective. North Korea is extremely mountainous and marked by deep, narrow valleys. A complex system of ranges and spurs extends across the country in a generally northeast to southwest direction. Most of the soils in the mountainous regions lack organic material and are relatively infertile. Only 18 percent of the land is arable. Nearly all the major rivers arise in the mountains and flow west to the Yellow Sea. Korea’s 636-mile boundary with China is formed by two rivers, the Yalu to the west and the Tumen to the east. This abutment of the two countries almost ensured eventual Chinese intervention in the conflict, which China did join in October 1950. The last eleven miles of the Tumen’s course separate Korea from Russia. The boundary between the two Korean states is known as the Military Demarcation Line, so designated by the Armistice Agreement of 1953; it replaced the division at the thirty-eighth parallel agreed upon by the United States and the Soviet Union in 1945. The total area of North and South Korea is about 85,300 square miles. North Korea has approximately 47,300 miles, about 55 percent of the total land area, and South Korea has roughly 38,000 square miles.


Advised and equipped by the Soviets and with huge reserves of manpower, the North Korean surprise attack was a smashing success. With more than 1,400 artillery pieces and 126 modern tanks from the Soviet Union, the North Korean force of 110,000 soldiers quickly drove through the ill-equipped, outnumbered South Korean forces. By the third day of the invasion, the Northern forces had captured the South Korean capital, Seoul. In contrast to the Soviets’ equipping of their North Korean ally with military supplies, the United States refused to aid South Korea in a similar way because it feared that South Korea might use its military strength to invade North Korea, which could lead to a major conflict between the United States and the Soviet Union.

It is believed that Soviet staff officers proffered advice in the drawing of the overall plan for an invasion and conquest of South Korea (Catchpole 2000, 11). The plan’s objective was to occupy all of South Korea within fourteen to fifteen days of the invasion and to unify the peninsula under Communist control. Following Stalin’s advice, the North Koreans significantly reduced their activity along the thirty-eighth parallel to lull the South Koreans into a false sense of security. Moreover, the attack was timed for Sunday morning, a time when many South Korean officials and their American advisers were away from their units on weekend passes. This also contributed to the success of the North Korean surprise attack.

Causes of the War

The war cannot be attributed solely to Kim Il Sung’s desire to reunify Korea under the Communist regime and the ideological disparity between the two Koreans instigated by the surrounding major powers. The war was also the result of an imbalance of power: The United States failed to study the strategic importance of the peninsula and balance the military strength of the two sides. In this sense, the war was in many aspects a result of the failure of deterrence (Gye-Dong Kim 1989, 45). As Hyung-Kook Kim (1995) points out, the origins and nature of the Korean War are best understood when looked at as two different wars fought in one theater at the same time.

The Korean War has major characteristics of civil war and can be considered as a domestic power struggle between Syngman Rhee and Kim Il Sung. The North Korean leader may well have had aspirations like those of Syngman Rhee—to unify the Korean peninsula immediately (by force if necessary) and then to assume leadership of all Korea—ever since the establishment of his separate regime. Kim Il Sung and Syngman Rhee were fiercely nationalistic, and each was determined to reunite the country under his own rule (Stueck 2002, 69).

Ideological and historical circumstances also contributed to some of the Communists’ miscalculations. Kim Il Sung overestimated the prospects for internal disruption in South Korea because his leftist ideology led him to see widespread popular discontent as omnipresent in the capitalist world (Stueck 1995, 355). Recent Communist success in China reinforced this misperception.

The policy of the United States toward Korea also played a role in encouraging Kim’s invasion. Had the United States made clear its intention to defend South Korea, the war could probably have been avoided. Despite the instability of the Rhee regime and considerable opposition from the State Department in Washington, which was concerned about the military threat to South Korea from North Korea, the United States hoped to withdraw from Korea as soon as possible. Kaufman (1999) notes that military leaders at that time believed that Korea lacked military and strategic value in a potential war in Asia (Kaufman 1999, 6). They were reluctant to make a military commitment in Asia after the Communist victory in China. Owing to a general manpower shortage in the United States armed forces, the military was reluctant to expand responsibilities. Moreover, they viewed that Europe would be the main area of confrontation with the Soviet Union. They believed that the greatest danger from the Soviet Union would come from a Communist takeover of the economically devastated nations of Western Europe. Prior to 1950, as Kaufman (1999) notes, U.S. officials in Washington perceived the immediate Soviet menace as directed primarily against Western Europe and, to a lesser extent, against the northern tier of Near East countries that included Greece, Turkey, and Iran.

In their view, Moscow sought to achieve its ambitions not through acts of overt military aggression but through subversion of economically destitute governments. Accordingly, the United States planned to protect Western Europe from Soviet expansion by economic assistance (as provided by the Marshall Plan of 1948) and collective security (as embodied in the formation of the North Atlantic Treaty Organization [NATO] in 1949). During the preceding periods, Korea had been a low priority. The military’s desire for an early withdrawal stemmed from this low strategic standing and from limited U.S. military resources (Chull Baum Kim 1994). The withdrawal of U.S. troops from South Korea, combined with the speech by Secretary of State Dean Acheson, encouraged the North Korean leader to pursue his invasion plan (Rees 1988).

In that speech at the National Press Club in Washington in January 1950, Acheson stressed UN protection for places beyond the U.S. “defensive perimeter.” The intent of this speech was to alert mainland Communist China that the United States would not act militarily to prevent an invasion of Taiwan and that there was no need to launch an attack on Chiang Kai-shek’s Nationalist government there. However, the speech also seemed to indicate that the United States would not act to protect South Korea from attack by its northern neighbor and that the country was outside the sphere of American concern in the Pacific. This omission, albeit unintentional, encouraged North Korea and the Soviets. Combined with the 1948 South Korean elections and the 1949 U.S. military withdrawal from the peninsula, American policy indicated a lack of desire to repel an invasion by North Korea. It was viewed within the United States as unlikely that the Soviet Union would allow such an attack to take place. When the invasion did occur, it dumbfounded the United States.


Conflict Status

Early Sunday morning on June 25, 1950, at 4 a.m., North Korea crossed the thirty-eighth parallel and attempted to unify the peninsula using quick and decisive force, believing that a response from the United States and its allies would be delayed or nonexistent. According to MacDonald (1996), Kim Il-Sung seemed oblivious to the possibility that the United States would defend South Korea, that the United States would not tolerate losing South Korea to communism. But this presumption, or failure to presume, proved false: By the end of June, the United Nations had created an international force under the command of U.S. Army General Douglas MacArthur to defend South Korea.

After the UN forces defeated North Korea, the UN General Assembly supported a U.S. proposal to occupy the North until elections could be held for a unified government. But this proposal would not be carried out. The Chinese, alarmed at the UN forces’ drive north across the parallel and toward their frontier, intervened. They deployed a large force of the Chinese People’s Volunteer Army as support for the North. The combined North Korean and Chinese forces pushed the UN back south of Seoul before a UN counteroffensive finally moved the front lines back to the thirty-eighth parallel in March 1951.

In June, the Soviet representative to the United Nations proposed cease-fire talks. These negotiations went on for two years while Korea continued fighting. The armistice between the UN commander and the combined forces of the North Korean People’s Army and the Chinese People’s Volunteers would not ultimately be reached until July 1953. South Korean President Rhee disagreed with this move; he insisted on Korea’s unification and objected to returning to a policy of containment. In his letter to President Dwight Eisenhower of May 30, 1953, he stated that the Korean question should be solved by punishing the aggressor and by reuniting the country. He even unilaterally released 28,000 prisoners in an attempt to prevent the agreement from being finalized. The United States responded to Rhee’s obstinacy by offering a mutual defense treaty: US $1 billion in economic aid over three years and equipment for a twenty-division army. Rhee acquiesced, but South Korea never signed the armistice.

The cease-fire was signed by China and North Korea on the one side and the United States on the other. The armistice agreement was effective without the signature of the South Korean government because international law authorized military commanders to conclude an armistice (Kleiner 2001). This cease-fire has not been converted into any permanent peace settlement. Therefore, the Korean War is not technically over—which makes the Armistice Agreement of 1953 the longest cease-fire in history. The new Military Demarcation Line agreed on by the two sides in the truce was based on natural defenses of water and terrain. To the north and south of the four-kilometer-wide Demilitarized Zone (DMZ) stand North Korean troops on one side and South Korean and American troops on the other. The DMZ is still defended today.

The Korean War, having resolved nothing and ending in a stalemate, left an estimated 1.3 million to 2.4 million Koreans dead. Nearly 37,000 U.S. troops were killed and another 103,000 wounded. An estimated 900,000 Chinese troops were killed and wounded. Turkey, Britain, Canada, France, Australia, Greece, and other UN countries lost between 2,000 and 3,000 troops (Clark 2000).

Duration Tactics

Although more than three years separated the outbreak of the military conflict and the armistice agreement, this superfluous length of time cannot be considered any side’s tactic to prolong the war. The reasons for the painful prolongation of the war are twofold: the intervention of China in October 1950 and the lengthy armistice negotiation. The most heated period of the Korean War was from June 1950 through March 1951; the rest of the war involved minor territory change and laborious peace negotiations.

At the end of September 1950, after a successful amphibious landing at Inchon, most South Korean territory was in the hands of UN troops. At this juncture, there was a discrepancy between South Korea’s and America’s objectives. When the war first broke out, Secretary of State Acheson stated that the fighting had the sole aim “of restoring the Republic of Korea to its status prior to the invastion from the North” (Spanier 1959, 88). As this objective had been achieved, there was no reason for the UN forces to cross the thirty-eighth parallel. However, the South Korean government, which had dreamed of reunification, could not be satisfied with restoration of the status quo that existed before the war. Syngman Rhee felt that the war would remain unresolved unless unity was achieved. The United States eventually converted to Rhee’s opinion in the hopes of reducing the Soviet’s influence. The United States changed its policy from one of containment to one of rollback (Kleiner 2001), a decision that would profoundly change and greatly prolong the course of the war in Korea.

From April 1951 until the end of the war in July 1953, the war’s front remained near the thirty-eighth parallel. In the spring and summer of 1951, the Chinese and North Korean forces tried to retake Seoul. But the front was almost impassable. After this failure, in the spring of 1951, China and North Korea started to reconsider the negotiations (Kleiner 2001). On June 23, the Soviet ambassador to the United Nations revealed a willingness to compromise on a cease-fire and truce. The first negotiation meeting was held on July 8, 1951. But this bargaining proved to be a much more involved process than either side expected. Three main issues in the negotiations were determination of a demarcation line for the cease-fire, establishment of a framework for supervising the armistice, and repatriation of the prisoners of war. Had it not been for the issue of repatriation, an end to the hostilities might have been achieved as early as 1951, two years before the final agreement was reached.

The cause of delay was President Truman’s opposition to the repatriation of POWs (prisoners of war) against their will, even though the Geneva Conference of 1949 specifically required all POWs to be repatriated regardless of their consent (Kaufman 1999). On July 8, 1953, it was agreed that those POWs who did not insist on being repatriated would become civilians six months after the conclusion of the armistice agreement. On July 27, 1953, the armistice agreement was finally signed.

External Military Intervention

The invasion of South Korea came as a shock to the United States. Dean Acheson of the State Department had told the U.S. Congress on June 20 that war was unlikely. It was also explicit in his testimony, in 1951, that all agencies of the American government were in accord: An invasion from by North Korea did not appear imminent. However, the CIA reported in early March that such an action was likely and could happen as early as June.

On hearing of the invasion, the United Nations and the American government reacted quickly and decisively. On June 25, the UN Security Council passed the first of three resolutions on Korea that would place the world organization’s full authority behind South Korea. During these resolutions, the Soviet delegate to the Security Council was absent in protest of the UN’s refusal to recognize the new Communist regime in China. Without the USSR’s veto, the motions passed easily. The first Security Council resolution called for a cease-fire, the withdrawal of North Korea forces to the thirty-eighth parallel, and an understanding that all UN members would render every assistance to the UN in the implementation of its decision. On June 27, the Security Council met again and called on the UN members to furnish such assistance. The Republic of Korea needed help to repel the armed attack, and the UN would need assistance to restore international peace and security in the area. With the Soviet’s absence and with the Socialist Federal Republic of Yugoslavia abstaining, on June 27 the UN voted to aid South Korea.

Meanwhile, the Soviets claimed that the Korean conflict was an internal affair and therefore outside the Security Council’s jurisdiction. They contended, moreover, that because the ruling had been decided in the absence of their delegate, any action taken by the UN would be illegal. Despite the Soviets’ accusations, President Truman authorized the use of U.S. naval and air assistance to South Korea. On another front, he also ordered Seventh Fleet to protect Taiwan, both to deter any Communist Chinese aggression toward the island and to dissuade the Chinese Nationalists from military actions toward the mainland. The United States still had substantial forces in Japan, which allowed for such quick intervention. General Douglas MacArthur, in charge of overseeing Japan as Supreme Commander for the Allied Powers and head of American forces in the Pacific, made a trip to Korea to understand the situation there. Following the visit, he asked permission from Washington to use American ground forces from Japan to stop the North Koreans. Truman gave the go-ahead. American combat troops would be sent from Japan to the southeast side of Korea to defend the Pusan area. The first American combat troops from the 24th Infantry Division in Japan arrived at Pusan on July 1, 1950.

The third major policy resolution concerning Korea was made on July 7, 1950. In this, the UN Security Council recommended that UN members providing military assistance under the previous resolutions should make their forces available to a Unified Command (UC) under the United States. The Security Council also authorized the Unified Command to use the United Nations flag concurrently with the flags of the nations participating, in the course of operations against North Korean forces. The United States, asked to designate a commander of the UC, quickly named General MacArthur. Sixteen nations were to send forces to the UNC, another five would send medical units, and forty members would offer aid. Eventually, U.S. forces were joined by troops from fifteen other UN member countries: Canada, Australia, New Zealand, the United Kingdom, France, South Africa, Turkey, Thailand, Greece, the Netherlands, Ethiopia, Colombia, the Philippines, Belgium, and Luxembourg.

After a successful landing at Inchon, the United Nations troops drove the North Koreans back past the thirty-eighth parallel. The goal of restoring the original border between the two Koreas had been achieved, but because of the heady success and the tempting possibility of uniting all of Korea under the government of Syngman Rhee, the Americans decided to continue their drive into North Korea.

This move greatly concerned the Chinese, who worried that the UN forces would not stop at the Yalu River, the effective border between the PRK and Manchuria. Their concern was not without reason, as many in the West, including General MacArthur, thought that spreading the war into China would be necessary. Truman and the other world leaders disagreed. So MacArthur was ordered to be extremely cautious when approaching the Chinese border. Amphibious and airborne operations north of the thirty-eighth parallel could be conducted only if there were no entry or threat of entry by Chinese or Soviet forces. South Korean troops only were to be used near the Soviet or Chinese borders.

The People’s Republic of China had issued warnings that if this mandate was not observed, they would intervene. On October 2, 1950, the Chinese Foreign Minister, Chou En-lai, told the Indian ambassador in unambiguous language that although South Korean entry into the North was not significant, American intrusion would be resisted by China. Truman regarded the warnings as a bluff—or worse, blackmail. So, disregarding the threat, U.S. troops crossed the parallel and moved into North Korea.

On October 8, 1950, the day after American troops crossed the thirty-eighth parallel and the UN passed its resolution on Korean unification, Chairman Mao ordered large-scale Chinese military intervention. He issued orders for the deployment of the Chinese People’s Volunteer Army to be moved to the Yalu River and to be prepared to cross. On October 15, Truman went to Wake Island to discuss the likelihood of Chinese intervention and his desire to limit the scope of the Korean conflict. MacArthur reassured his commander that there was very little chance of Chinese intervention and that, in any case, his air force was capable of inflicting sufficient destruction on any Chinese ground troops entering Korea.

MacArthur’s assurances were misinformed. The Chinese assault began on October 19, just four days after the general’s bravado, and was led by General Peng Dehuai in command of 300,000 CPVA troops. The Chinese assault caught the UN troops by surprise, as war between the PRC and the United Nations had not been declared. The Battle of Chosin Reservoir (November 26-December 13) forced the UN deployment to withdraw from the northern part of Korea. The United States X Corps retreat was the longest retreat of an American unit in history. At the end of December 1950, North Korea was back in Communist hands. On January 4, 1951, Seoul was retaken by Communist Chinese and North Korean forces. Both the Eighth Army and the X Corps were forced to retreat.

On April 11, 1951, President Truman relieved MacArthur of his command. The general was seen as having overstepped the bounds of his military responsibilities (Kleiner 2001). These missteps include his meeting with ROC President Chiang Kai-shek in the role of a U.S. diplomat. He had also shown poor foresight at Wake Island when President Truman asked him specifically about Chinese troop buildup near the Korean border. Furthermore, MacArthur had openly demanded the authority to use a nuclear attack on China. He felt it was high time to counter Communism in an offensive, aggressive way. His view, although in perfect agreement with the Republicans, proved his undoing. His successor was General Matthew Ridgway, who managed to regroup the UN forces for an effective counteroffense that slowly but steadily drove back the opposing forces.

Conflict Management Efforts

In imposing military sanctions against North Korea, the United Nations had taken an extraordinary step. The UN also promoted efforts toward a cease-fire to end the Korean conflict and later negotiated a solution to the POW issues. To facilitate the implementation of the armistice, shortly after the agreement to a truce a new Joint Security Area (JSA) was set up in the Demilitarized Zone at Panmunjom. Both parties agreed that a permanent detail of joint duty officers from the United Nations Command and the Communist side would be stationed in the JSA.

Three commissions were created to supervise this cease-fire. The Military Armistice Commission (MAC), which consisted of senior representatives of both sides, would exercise overall supervision of the truce via joint observer teams in the DMZ. The main work of the MAC was to hear the accusations and counteraccusations launched over truce violations in the DMZ.

The second agency created by the armistice was the Neutral Nations Supervisory Commission (NNSC). The NNSC was originally created to inspect for and ensure armistice compliance at locations outside the DMZ. Under the armistice agreement, it originally consisted of delegations from four nations: Sweden and Switzerland (nominated by the United Nations Command and Czechoslovakia and Poland (appointed by the Communists). North Korea declared this body defunct in April 1991 and began boycotting their events. The grounds for this accusation were that the countries they nominated were no longer Communist. When Czechoslovakia split in two in 1993, North Korea refused to accept the Czech Republic as the replacement and forced the withdrawal of their delegation. In February 1995, North Korea forcibly ejected the Polish delegation from North Korea. Today, only the Swedish and Swiss delegations play this role on a full-time basis; the Polish delegation, which never accepted its dismissal, occasionally returns to Panmunjom to participate in NNSC functions.

The third agency was the Neutral Nations Repatriation Commission (NNRC). This agency was to supervise the exchange of POWs, their repatriation, and the eventual disposition of prisoners in neither category. After its initial work on POWs was complete, the NNRC voted to dissolve itself in February 1954.


The border between North and South Korea remains highly armed and tense half a century after the start of the bitter war that divided the peninsula. The Korean War had a profound impact on the fate of Koreans residing in their native land. The war left almost 3 million of their countrymen dead or wounded and millions of others homeless and separated from their families. Globally, the current crisis of North Korea’s nuclear threat is also a by-product of the division of the Korean peninsula and therefore a result of the Korean War.

But the debate on the origins of this war continues. Understanding the interplay of domestic and foreign forces is the key to understanding the Korean War (Lone and McCormack 1993). Hyung-Kook Kim (1995) argues that the Korean War must be understood in a wider theoretical framework, not just as a civil war or as American intervention against Communist aggression. As these scholars argue, the origins of the war must be understood in the context of events both inside and outside Korea.