Use the following graph and what you know about American military involvement to answer the question below:

This is a line graph titled United States Defense Budget. The y-axis shows Billions of Dollars from 0 to 800 in 100-dollar increments. The x-axis shows years and ranges from 1948 to 2008. The line peaks at 1954, 1969, 1987, and 2008. It dips most heavily at 1949, 1957, 1975, and 1999.

What accounts for the spikes in American defense spending in the 1950s?

The entry of the U. S. into the UN
The Afghan War
The Vietnam War
The Korean War