Perhaps you have in mind the Monroe Doctrine (and Theodore Roosevelt's Corollary and Manifest Destiny). If so, you will find information about those justifications for U.S. influence at http://www.state.gov/r/pa/ho/time/jd/16321.htm
The United States proclaimed itself as the protector of the Western Hemisphere through the Monroe Doctrine in 1823. The doctrine stated that the Americas were off-limits for European colonization and that any interference would be seen as a threat to U.S. security.
the monroe doctrine
the monroe doctrine
Western hemisphere.
The Roosevelt Corollary
yes
James Monroe(: he made the monroe doctrine
Monroe Doctrine
Would take care of the Western Hemisphere without assistance or interference from the Olde World.
The US is in the Northern hemisphere, and in the Western hemisphere. :3
After the revolution the US stated that any attempt to colonize the western hemisphere would not be tolerated, and would be dealt with militarily.
It is in a north western hemisphere