Question

Why did president Roosevelt begin the good neighbor policy

Answer 1

The Good Neighbor Policy was the foreign policy of the administration of the United States President Franklen Roosevelt towards Latin America. Although the policy was implemented by the Roosevelt administration, President Woodrow Wilson had previously used the term—but subsequently went on to invade Mexico. Senator Henry Clay had coined the term Good Neighbor in the previous century.
I got this off wiki, so credit to them. :-)
Hope this helps! :-)