The foreign policy of William Howard Taft was largely a continuation of Theodore Roosevelt's, particularly as it related to Latin America. Both presidents advocated an active, even interventionist foreign policy, an approach often called "big stick" diplomacy under Roosevelt. Taft's presidency saw the advent of what became known as "dollar diplomacy." Under Taft, the United States government began to guarantee loans to foreign countries in an effort to keep European interests out. This was entirely consistent with the Roosevely Corollary to the Monroe Doctrine, which asserted the US right to intervene in countries where political stability left them open to European military efforts to protect financial interests. Under "dollar diplomacy," the United States would simply buy up debts owed by Latin American nations to European banks, or simply make new loans from the United States. Either way, the United States would gain considerable leverage over the nation in question. Nicaragua and Haiti both received millions in American loans, and were both invaded by American marines to secure the ensuing debts. Taft also encouraged, as Roosevelt had, investment in infrastructure, particularly railroads, in China. As in other aspects of the two presidencies, the chief difference between the two was perhaps temperamental and rhetorical.
Teddy Roosevelt was an interventionist, meaning he intervened in foreign affairs. His Roosevelt Corollary to the Monroe Doctrine meant that he endorsed intervening in countries in Latin America. His policy, referred to as "speak softly and carry a big stick," meant that he supported American intervention and force when necessary to support American imperialism. He did so, for example, to build the Panama Canal. To win concessions to build the canal, Roosevelt supported a revolution in Panama to break away from Columbia in 1903, and the U.S. began constructing the canal in 1904.
Taft, on the other hand, used investment to support American diplomacy--a practice called "dollar diplomacy." His policies and interventions abroad, such as his use of American troops to quell rebellions in Nicaragua and Honduras, were guided by American business interests. He pursued a free-trade agreement with Canada in 1911 to lower tariffs on goods traded between the U.S. and Canada, but the Canadian Parliament rejected the deal. Taft was not guided by any overarching idea about the role of America abroad, as Roosevelt was, but was instead interested in protecting American business interests.