The North Korean communist forces wanted to take South Korea and unite the country under communism. The United States organized a United Nations operation to stop this because they feared that fall of Korea could spread throughout all of Asia. They managed to beat back the North Korean forces before China interfered when UN attacked northern territories.
The second is the Vietnam war
A very similar situation occurred in Vietnam however the outcome was different. This wasn't a UN operation but rather a United States one out of the same fears. However, the United States had to leave Vietnam and it fell to communism which then spread to Cambodia and Laos. This sparked mass fear in the United States.
The third can be the Soviet Invasion of Afghanistan
In the 70s, the Soviet Union invaded Afghanistan and wanted to spread communism there. Local nationalists organized a rebellion in order to overturn the government and install a Mujaheddin government. The Soviets were defeated and the Afghan war ended later with Mujaheddin winning. During the war, they had United States help.
The Bush Doctrine of the early 2000's can be best described as idealism and unilateralism. At the time, the <span>United States became engaged in policies across the globe that were driven by neoconservative ideology.</span>
We require the some more information regarding the very specific novel( what ever the genre may be). As, there should be a given paragraph or some phrases that are required to add more value to the given answer which is desired by the student in a given manner. As each of the plot relation to the possible theme of the unknown novel will be easy to be evaluated.