The road to independence was especially violent in Laos, Cambodia, and Vietnam (all formerly part of French Indochina). What caused the United States to get involved?

Reasons why United States involved in Road to Independence:

Laos, Cambodia and Vietnam were French protectorates for many years and their road to independence resulted in the Indochina War which was thought for 30 years. The US got involved in the war to prevent communism but it also had an interest in foreign policies, national fears, economic interests and geopolitical strategies.

In that era, most Eastern European countries were under communist rule, and communism was fast spreading to other parts of the world including Latin America, Africa and Asia. The US involvement in Indochina battle was a tactic to contain communism.