This question is incomplete, here´s the complete question.
What was Kennedy's main reason for supporting the United Nations?
He did not want it to be a forum for invective.
He thought it would help nations to resolve problems peacefully.
He thought it would help to enhance the world's image of the United States.
He thought the instruments of war had outpaced the instruments of peace.
Answer: He thought it would help nations to resolve problems peacefully.
Explanation:
The 35th President of the United States (1961-1963) showed support for the UN as a means to end a horrific past doomed by war, and to ensure a peaceful future. In his speech to the U.N. General Assembly on September 20, 1963, he stated that in order to avoid "conflict and crisis", he wanted to "salute the United Nations and to show the support of the American people for your daily deliberations.”