From the assertion of the Monroe Doctrine in 1823 to the Reagan Doctrine of the 1980s, the United States has presumed a position of political leadership and pre-eminence in the Western Hemisphere. This has been made possible by two main factors: America's huge economy, which has made the U.S. the largest single commercial market and the biggest investor in Latin America, and America's military prowess, which has been convincingly demonstrated in victories...