The Cold War, Korean Conflict, and Vietnam

 

President Harry S Truman holds a newspaper that wrongly announced his defeat by Republican candidate Thomas Dewey in the 1948 election.

(The following article is taken from the U.S. Department of State publication, USA History in Brief.)
The United States played a major role in global affairs in the years immediately after World War II, especially through its influence in the newly formed United Nations and North Atlantic Treaty Organization (NATO). The most important political and diplomatic issue of the early postwar period was the Cold War. It grew out of long-standing disagreements between the United States and the Soviet Union over which type of government and economic system produced the most liberty, equality, and prosperity.

U.S. infantry fire against North Korean forces invading South Korea in 1951, in a conflict that lasted three painful years.

Faced with a postwar world of civil wars and disintegrating empires, the United States hoped to provide the stability to make peaceful reconstruction possible. It advocated democracy and open trade, and committed $17,000 million under the "Marshall Plan" to rebuild western Europe. The Soviet Union wanted to secure its borders at all costs. It used military force to help bring Communist regimes to power in Central and Eastern Europe.
The United States vowed to contain Soviet expansionism. It demanded and obtained a full Soviet withdrawal from Iran. It supported Turkey against Soviet attempts to control shipping lanes. It provided economic and military aid to Greece to fight a strong Communist insurgency. And it led the effort to airlift millions of tons of supplies to Berlin when the Soviet Union blockaded that divided city.
With most American aid moving across the Atlantic, little could be done to prevent the Communist forces of Mao Zedong from taking control of China in 1949. When North Korea – supported by China and the Soviet Union – invaded South Korea the next year, the United States secured U.N. support for military intervention. The North Koreans were eventually pushed back, and a truce was signed, but tensions would remain high and U.S. troops would stay for decades.
In the mid-1960s, the United States sent troops to defend South Vietnam against a Communist insurgency based in North Vietnam. American involvement escalated greatly but was not enough to prevent the South from collapsing in 1975. The war cost hundreds of thousands of lives. It also caused bitter divisions at home, making Americans wary of further foreign entanglements.