The United States expanded its international influence significantly in the early 20th century. The Open Door Policy, for instance, promoted international trade between China, the United States, and several foreign countries. After Chinese nationalists, known as the Boxers, led an anti-foreign uprising that killed hundreds of Westerners, European nations threatened to carve China into spheres of influence. This worried the United States, which had recently gained access to Chinese markets with the annexation of the Philippines in 1898. Thus, between 1899 and 1900, Secretary of State John Hay wrote to Great Britain, France, Germany, Russia, and Japan outlining an international trade agreement that would retain open trade in China for those nations and keep China geographically and administratively intact, allowing it to collect taxes and other trade-related duties.
Except for China's perennial rival, Japan, all of the nations agreed, and the agreement became official U.S. policy for the next 40 years. Four years later, President Theodore Roosevelt shifted attention back to the Western Hemisphere with the Roosevelt Corollary. The Roosevelt Corollary, also known as Big Stick Diplomacy, expanded the 1823 Monroe Doctrine, in which the new nation declared that it would view any act of European colonization in the Western Hemisphere as an act of war.
Roosevelt's new policy established the United States as the Western Hemisphere's most powerful nation, which could act as a self-appointed International police force by intervening in conflicts between Caribbean or Latin American countries and Europe. In 1905, for example, the United States repaid the Dominican Republic's debts to European nations and claimed the right to appoint a new leader in charge of customs in return. This move prevented European military intervention and set a model for U.S. interference in Latin America for years to come. In another move exemplifying big-stick diplomacy, Roosevelt ordered the Navy to sail an armada of battleships nicknamed the Great White Fleet around the world in 1907 to demonstrate the country's global might. Although strong, the Great White Fleet was still small compared to Europe's navies, and in the Pacific it faced threats from Japan, who was dissatisfied with a treaty Roosevelt brokered in 1905 to end the Russo-Japanese War.
Roosevelt's critics argued that launching the fleet wasted money and could antagonize Japan, yet it succeeded in impressing world leaders, including those in Japan. In 1909, President William Taft set a less militaristic tone. Inspired by events in the Dominican Republic, Taft hoped to influence nations through economic investment rather than global policing.
which meant encouraging U.S. businesses to invest abroad while promoting American ideals. Unfortunately, this policy led the United States to interfere in foreign politics. In Nicaragua, political interference caused civil unrest that later required U.S. military intervention. Ultimately failing to export American values and becoming instead a tool for interfering in foreign governments, Taft's policy earned the derisive name dollar diplomacy.