Korean War in 1950 (NSC)

Educator Overview

Case Overview

Set in September 1950. At the conclusion of World War II, Korea—formerly under Japanese control—was divided at the thirty-eighth parallel into a U.S.-occupied south and a Soviet-occupied north. Although the division was meant to be temporary, by 1948 both countries had declared independence. North Korea became a Soviet-supported communist state; South Korea was supported by the United States. Two years later, North Korea invaded South Korea in an attempt to bring the entire peninsula under its control. After several weeks of fighting, U.S. and South Korean forces were defending an area called the Pusan perimeter, in the southernmost portion of the peninsula. General Douglas MacArthur, who was commanding U.S. and allied forces as part of a UN mission, was also making plans for a landing at Inchon, near the South Korean capital of Seoul, in order to surprise North Korean troops and recapture Seoul.  

Anticipating the possible success of the Inchon landing, President Truman has convened National Security Council members to advise him on whether to extend the U.S. military intervention north of the thirty-eighth parallel in an attempt to unify the Korean Peninsula. As the dividing lines of the emerging Cold War start to solidify, the United States will have to weigh whether intervention in North Korea is worth a potential conflict with another great power.

Decision Point

President Truman has convened National Security Council (NSC) members to advise him on whether to extend the U.S. military intervention north of the 38th parallel in an attempt to unify the Korean Peninsula. The president has made clear that this decision depends on the success of the Inchon landing and victory in South Korea. It is also clear that NSC members will need to consider a few critical questions. First, what is at stake in the conflict? Is it just a Korean national issue, fueled by North-South rivalry, each side seeking to lead a unified nation, or could the conflict become a major flash point in the Cold War? Second, what are the chances of Soviet or Chinese intervention if the United States invades North Korea? Finally, does reunifying Korea offer a better prospect of a durable peace than stopping at the thirty-eighth parallel would? 

Learning Goals

CFR Education simulations use a variety of pedagogical tools to create an effective, meaningful, and memorable learning experience for students that builds their global literacy. Students will develop crucial skills such as critical thinking, communication, collaboration, and creativity. Students will complete authentic assessments that feel relevant: instead of five-paragraph essays and book reports, students will write policy memos and participate in a role-play of a meeting of a foreign policy–making body. There are no right or wrong answers in actual policy deliberations, and there are none here, either; students will walk away from this experience with an appreciation for the complexity of policy questions.

In this simulation, students will learn about the National Security Council, as well as meeting these learning outcomes specific to this simulation:

  • Students will understand the factors that led to the Korean War as well as the broader context of the Cold War policy of containment.
  • Students will consider the complexities of the U.S. decision-making process during the Korean War.
  • Students will evaluate the potential benefits and drawbacks of pursuing Korean unification through military action.

Concepts and Issues



  • U.S. support for democratic governance
  • Costs, benefits, and risks of military interventions
  • U.S. interests in East Asia
  • The UN Security Council and the U.S. role at the United Nations
  • Early flash points in the Cold War
  • Security and diplomacy in Northeast Asia
  • Chinese and Soviet support of North Korea

Policy Options: Educator's Guide

This section presents context, potential benefits and drawbacks, and other information about the policy options outlined in the case that you may find helpful as you guide the role-play and assess students. 

Inside the Truman administration, arguments over what the United States should aim to do in Korea began almost as soon as the North Koreans invaded the south. Perhaps the most critical question was whether and how China or the Soviet Union would intervene if the United States tried to reunify the Korean Peninsula. 

On the one hand, Truman was cautious. He sought to ensure that the United States would not overcommit to Korea or slip into conflict with Moscow. As he wrote in his memoir Year of Decisions, “Every decision I made in connection with the Korean conflict had this one aim in mind: to prevent a third world war and the terrible destruction it would bring to the civilized world. This meant that we should not do anything that would provide the excuse to the Soviets and plunge the free nations into full-scale all-out war.” On the other hand, administration officials recognized a potential opportunity to deal a devastating blow to global communism and reunify Korea under a democratic, U.S.-backed government. 

The initial U.S. goal, in the opening weeks of the conflict, was simply to drive the North Koreans back to their own territory. Truman agreed with an early suggestion by Secretary of the Army Frank Pace that U.S. military operations north of the thirty-eighth parallel should be strictly limited. He authorized military operations with the specific goal of restoring that parallel as the border. 

Many administration officials, though, advanced the view that U.S. aims should go further. John Allison, director of the State Department’s Office of Northeast Asian Affairs, was among them. In a July 1, 1950, memo to Assistant Secretary of State for Far Eastern Affairs Dean Rusk, Allison wrote, “I am convinced that there will be no permanent peace and stability in Korea as long as the artificial division at the 38th parallel continues.” Other major State Department figures, including advisor John Foster Dulles, generally shared a desire to pursue full unification of the peninsula. They were more cautious than Allison, however, and feared war with the Soviet Union or China. 

Military leaders, for their part, were eager to proceed north of the thirty-eighth parallel, though their foremost goal was not necessarily to reunify the peninsula. Instead, it was to devastate the North Korean military so that it could not invade South Korea again. Chairman of the Joint Chiefs of Staff Omar Bradley wrote in his autobiography "A General’s Life" that this was the military’s “unanimous” position: “We believed that MacArthur should not be restrained at the 38th parallel.” 

This view certainly pleased MacArthur, who had ambitions of occupying and reunifying the entire peninsula. In mid-July, just weeks after the war began, MacArthur told other military leaders, “I intend to destroy and not to drive back the North Korean forces. I may need to occupy all of North Korea.” On August 8, W. Averell Harriman, special assistant to the president, met MacArthur in Tokyo. MacArthur, in Harriman’s telling, was confident that elections could be held in both North and South Korea following a military victory—and that MacArthur had “no doubt of an overwhelming victory for the non-Communist parties” in both the South and the North. 

The opposite view—that the United States should limit itself to pushing the North Koreans back—was less widespread during the summer of 1950. Some officials, though, did counsel restraint. This perspective came most notably from the State Department’s policy planning staff, a unit intended to provide analysis that goes beyond day-to-day issues. George Kennan, who had established the staff and served as its first director, was one of the loudest voices warning of the potential risks of intervention north of the thirty-eighth parallel. Kennan’s successor as director of the policy planning staff, Paul Nitze, and other members of the unit shared Kennan’s skeptical view. A July 22 draft memo prepared by the one staff argued: “The disadvantages of a failure to attain the complete independence and unity of Korea after the North Korean forces have been driven back to the 38th parallel must be weighed against the risk of a major conflict with the USSR or Communist China that such a settlement might well involve.” In other words, stopping U.S. action at the thirty-eighth parallel would be bad, but war with the Soviets or Chinese could be worse.