Why was the United States described as a "police officer" in Latin America under President Theodore Roosevelt?
Roosevelt said the US would prevent Latin American countries from illegal actions.
Latin American countries were newly formed countries after WWI with U.S.A.
Later, U.S.A grew in power due to its vast resources and developed manpower.
For strengthening its base in South America it guaranteed independence to (mainly) all South American countries.
It also helped them in sore times. So, The United States is described as a "police officer" in Latin America under President Theodore Roosevelt's reign.