It illustrates the Roosevelt Corollary, in which the United States will use force to keep European nations from colonizing Latin America.
For many years, the Monroe Doctrine was practically a dead letter. The bold proclamation of 1823 that declared the Western Hemisphere forever free from European expansion bemused the imperial powers who knew the United States was simply too weak to enforce its claim. By 1900, the situation had changed. A bold, expanding America was spreading its wings, daring the old world order to challenge its newfound might. When Theodore Roosevelt became President, he decided to reassert Monroe's old declaration.