Question

When was the tipping point at which the United States could no longer be considered an isolated nation?
At what point could the United States no longer avoid involvement in World War II?

Answer 1

World War 1, not for sure but I would be highly close because that is the first time that I know we became involved in the other worlds problems.
It became increasingly harder because of the sinking of a merchant ship the Lusitana and Germany sending a letter to Mexico saying attack the US well give you land and Well Obviously, Pearl Harbor.