Why did the united states enter the vietnam war?

Question: Why did the united states enter the vietnam war?

The main reason behind the United State's involvement in the Vietnam War is to prevent the spread of communism over the South East Asia. Vietnam was partitioned into North communist Vietnam and South democratic Vietnam. North Vietnam wanted to make it one with communism. America didn't want the spread of communism and hence send money, supplies and military advisers to help the South Vietnamese Government.