Isolationism was a foreign policy that was dominant in the American political arena throughout the majority of the nineteenth century. It argues that the United States will not get involved in foreign conflicts and will try to remain isolated on the international stage.

The League of Nations was part of Woodrow Wilson’s Fourteen Points, which he released on the eve of the end of World War One. The idea was to form an international body that would oversee international affairs and try to prevent another global conflict from breaking out. It failed in part due to a lack of support in the United States: it failed even to pass Congress, much to Wilson’s dismay.

NATO was created in 1949 as an alliance of the United States, Canada, Western Europe, and Turkey to meet the perceived threat of the Soviet Union and the rise of communism. It was primarily a military alliance. Its opposition was the Warsaw Pact, which was formed shortly afterwards between Russia and the communist nations of the Eastern Bloc.

Appeasement is the term given to making concessions to a political or military rival in order to prevent said rival from doing something even worse. It has long been a controversial form of making policy and is most notable in US History for America’s reaction to the Japanese occupation of Manchuria in 1931.

Throughout the initial decades of the Cold War, the United States and the Soviet Union continued to acquire more and more nuclear weapons until each nation possessed the capacity to destroy the planet many times over. In an attempt to mitigate this massive threat to humanity, the two superpowers signed a treaty in 1972 designed to reduce the stockpile of nuclear weapons possessed by both nations. This took place during the presidency of Richard Nixon.

George Washington was particularly concerned about entering long-term alliances with foreign nations, fearing it would draw America into unnecessary conflicts. His fear of political factions warring over the government was a common fear among the founders, best expressed by Madison's Federalist No. 10. 

The idea of getting involved in foreign conflicts was incredibly unpopular in America, and the isolationist politicians in Congress tried to keep America out of both of the World Wars as long as possible before the United States eventually entered both of the wars late.

"Big Stick" Diplomacy refers to Teddy Roosevelt, the American president most commonly associated with aggressive shows of strength. Roosevelt argued that a good leader should speak softly, and carry a big stick. The big stick referring to the coercive strength needed to backup threats and diplomatic appearances.

The Roosevelt Corollary was made in the interest of intervention. While the original Monroe Doctrine was made solely to warn European nations away from the Western Hemisphere, the Roosevelt Corollary was made to name the United States as the policemen of the Americas.

The Drago Doctrine was announced by Argentina in response to European nations' aggressive debt-collecting actions during the 1902 Venezuela Debt Crisis. It declared that European nations were not allowed to coerce Latin American nations into paying their debts. Roosevelt rejected this Doctrine, and added the Roosevelt Corollary instead, allowing American intervention in countries that couldn't properly conduct their own affairs.