President John F. Kennedy decided to increase military aid to
South Vietnam without committing U.S. combat troops. He was concerned at the advances being made by the communist Viet 
Cong, but did not want to become involved in a land war in
Vietnam.

Kennedy hoped the military aid would be sufficient to strengthen
the Saigon government and its armed forces against the Viet
Cong. Ultimately it was not, and Kennedy ended up sending
additional support in the form of U.S. military advisors and
American helicopter units