Mahan suggests that an end to isolation is necessary because

Alfred Thayer Mahan was a United States naval officer and historian. His book  The Influence of Sea Power Upon History, 1660–1783 (1890) was widely acclaimed, especially in Europe.

In his book, Mahan argued that the power a nation has depends predominantly on its dominance of the seas. He also argued that the economic future of the U. S. depended on getting new markets abroad. This required an end to isolationism. It also required a powerful navy to protect these markets from foreign rivals.

a. favoring native born americans over immigrants.