Question

What event involving the United States brought about the need or desire to begin an expansionist policy with regard to foreign affairs?

the Mexican-American War
the Louisiana Purchase
the Spanish-American War
the Russo-Japanese War

Answer 1

It was the Mexican-American war that brought about the need or desire to begin an expansionist policy with regard to foreign affairs, since the end of this war ceded a lot of new territory that was used by settlers moving west.