During the Cold War, the United States adopted a policy of containing the spread of Communism. When and where did the United States first send large numbers of its soldiers overseas specifically to contain Communist expansion?

Introduction / Context:
One of the central themes of the Cold War was the policy of containment, through which the United States aimed to prevent the spread of Communism beyond areas already controlled by Communist governments. This policy shaped American foreign interventions around the world. The question asks you to identify the first major instance when the United States sent large numbers of its soldiers overseas specifically to contain Communist expansion. This focuses on the early application of containment doctrine in a real war situation.

Given Data / Assumptions:

• The context is the Cold War rivalry between the United States and the Soviet Union.
• The purpose of the intervention is to contain Communism.
• The options list several regions and years: Korea 1950, Vietnam 1965, Afghanistan 1979, and Cuba 1961.
• We assume standard Cold War chronology.

Concept / Approach:
The first large scale overseas deployment of United States combat troops to contain Communism took place in the Korean war. In 1950, North Korean forces, supported by Communist allies, invaded South Korea. The United States, under the banner of the United Nations, sent troops to support South Korea and to prevent the spread of Communism on the Korean Peninsula. Later, the United States also intervened in Vietnam in the 1960s, but that came after Korea. Afghanistan in 1979 mainly saw Soviet intervention, and the United States responded indirectly. The Bay of Pigs invasion in Cuba in 1961 involved a small force of Cuban exiles, not a large regular United States army. Therefore, the first major deployment clearly refers to Korea in 1950.

Step-by-Step Solution:
Step 1: Recall that the Korean war began in 1950 when North Korea invaded South Korea.Step 2: Remember that the United States, following its containment policy, quickly sent troops to defend South Korea under United Nations authorization.Step 3: Note that this deployment involved large numbers of regular United States soldiers in direct combat overseas against a Communist backed force.Step 4: Compare this with Vietnam, where major United States combat troop deployment escalated later, especially after 1965.Step 5: Recognize that Afghanistan and Cuba in the given years do not match the description of the earliest large scale overseas deployment for containment.

Verification / Alternative check:
History texts on the Cold War usually present Korea as the first major hot war of the Cold War era, and they describe it as a clear example of containment in action. The Truman Doctrine, announced earlier, promised aid to countries resisting Communism, but Korea was the first case where a large United States led military force fought overseas against Communist expansion. Vietnam is often mentioned later as the second major American war against Communism. The Bay of Pigs operation was a smaller covert style invasion, and United States involvement in Afghanistan during the 1980s was mainly through support to local fighters, not through large direct troop deployments. These details confirm that Korea in 1950 is the correct answer.

Why Other Options Are Wrong:
Vietnam in 1965 represents a later, large scale United States intervention to contain Communism but not the first such deployment.
Afghanistan in 1979 involves the Soviet invasion; the United States provided support to Afghan fighters but did not send large numbers of its own soldiers into direct combat.
Cuba in 1961 refers to the Bay of Pigs invasion, which used a small force of Cuban exiles supported by the United States, not a major overseas deployment of United States regular troops.

Common Pitfalls:
Students often associate the Vietnam war so strongly with the Cold War that they mistakenly think it was the first major containment war. Another common error is to confuse interventions involving advisers or covert operations with large scale troop deployments. To avoid these mistakes, remember that the Korean war from 1950 to 1953 was the earliest large scale overseas war in which the United States sent substantial regular forces specifically to block Communist expansion. Vietnam then followed as the next big conflict, not the first one.

Final Answer:
The United States first sent large numbers of its soldiers overseas to contain Communist expansion in Korea in 1950.