1) Democracy and military bases in Japan
After the surrender of the Japanese Empire, the United States subsequently installed a new democratic government in Japan, and installed military bases to have further influence in trade and naval supremacy in the region. This has led all the way to now when the United States uses its military bases and docks in Japan to guard the coast of Taiwan from China and patrol the seas next to North Korea.
2) Vietnam War
The Vietnam War was a proxy war between the United States and the former Soviet Union. Vietnam had split in half North/South in a civil war between Communism and Democracy, with the US supporting the south and the USSR supporting the north. The US' involvement in this war was heavily protested in the United States and was a major disaster for the US. The war ended in a loss and many American soldiers who were mostly drafted to fight died.