Answer:
After World War II much of Europe was destroyed. Armies from both sides had bombed roads, bridges, supplies, and communication facilities throughout Europe. Europe needed to rebuild.
This was not easy however. Many governments were in debt or out of money because they had used all their resources in fighting the war. On top of this, their economies were devastated making it difficult to collect taxes in order to rebuild. Many people did not have enough food to eat let alone money to pay taxes.
Fear of Communism
The United States, as well as much of Europe, had allied with the Russians in order to defeat Hitler and the Germans. However, now they were worried about the Russians and the spread of communism. If Western Europe did not rebuild and grow strong quickly, it may soon fall to communism.
Fortunately, the land of the United States had been free of war and devastation. The US economy was doing well, making the United States the richest country in the world. They wanted to help Europe and their allies recover from the War.
The University Of Kansas, February 1965
On June 25, 1950, the Korean Warbegan when North Korea, supported by the Soviet Union and China, invaded South Korea, which was supported by the United States. General MacArthur, leader of the United Nations forces, drove the North Koreans back across the divide, yet encountered a Chinese invasion.
Basically, the U.S was a fellow supporter of south korea, and that's how they got included.
Some of it could be belifes in what he belived in or it coukd be they just like him thought he was a chill cool nice guy all around or they were friends or family. hope this helps