Final answer:
France, through a series of strategic military and diplomatic moves in the mid-19th century, established colonial control over Vietnam before the United States got involved in the country.
Step-by-step explanation:
The world power that was in Vietnam before the United States was
France
, as evidenced by historical colonial control. This control dates back to the mid-19th century when
Napoleon III established control over Vietnam in a series of strategic military and diplomatic moves
. By 1887, France had exerted its influence over all of Vietnam. Even after World War II, France sought to reclaim control of Vietnam, which came to be known as the First Indochina War. The United States gradually became involved in the issue, initially by supporting France financially.
Learn more about French Colonial Control