US foreign policy in the nineteenth century was quite fluid. In the early part of the century, the United States fought a war with Britain, during the War of 1812. There were also concerns about the French and Spanish empires in North America. The United States purchased French Louisiana and encouraged South American countries to revolt against Spain though sent them no direct aid. The United States created the Monroe Doctrine in order to warn other European nations from meddling in Latin America, but the country lacked the strong military presence in order to make this anything more than a threat.
The United States did not involve itself in power struggles outside of North America. The United States declared war on Mexico during the Polk administration in order to expand its Western borders. The nation also sent a naval fleet to Japan in order to establish trade relations with the country. During the Civil War the Union threatened Britain and France with war if they overtly helped the Confederacy. After the war, Northern shippers won an arbitration meeting against Britain, winning a large settlement due to Britain building and equipping the Confederate privateer Shenandoah to attack Union shipping.
After the war the United States looked to expand yet again. The nation bought Alaska from Russia in 1867, a move that was criticized at the time but paid major dividends when gold was found in the region thirty years later. Sugar and pineapple growers from the United States overthrew the legitimate queen of Hawaii and petitioned to join the United States in order to get out of paying tariffs on their crops. Hawaii became a territory in 1898. The United States also declared war on Spain in order to force them out of Cuba, Puerto Rico, and the Philippines. While the listed objective for this war was to protect the people living in the area, economics were a major concern as the United States needed coaling stations and tropical cropland. The United States, though not having any formal treaties with European or Asian countries, had expanded a great deal during the nineteenth century. The century saw the country become a major player in North American affairs as well as have some overseas colonies.