When World War I broke out in July 1914, the United States actively maintained a stance of neutrality, and President Woodrow Wilson encouraged the U.S. as a whole to avoid becoming emotionally or ideologically involved in the conflict. …

Isolationists advocated non-involvement in European and Asian conflicts and non-entanglement in international politics. Although the United States took measures to avoid political and military conflicts across the oceans, it continued to expand economically and protect its interests in Latin America.

The so-called “internationalists” claimed that America’s security depended on the defeat of Germany, and called for providing whatever Great Britain and its allies needed to bring that about, save actual troops. The British, they maintained, represented the last great defense of democracy from Nazi tyranny.

In November 1939, two months after the beginning of World War II, Congress passed the Neutrality Act of 1939, which lifted the 1935 arms embargo and placed all sales to belligerent nations on a “cash and carry” basis.

Congress has the constitutional power to declare war and the Senate must approve treaties; the most relevant congressional actors in the foreign policy arena are the Senate Foreign Relations, Armed Services, and Homeland Security and Governmental Affairs committees, and the House Foreign Affairs, Homeland Security, and …

The “makers” of foreign policy include the president, various bureaucratic agencies and departments, and Congress. The “shapers” of foreign policy include interest groups and the media.

Under the Constitution, the President of the United States determines U.S. foreign policy. The Secretary of State, appointed by the President with the advice and consent of the Senate, is the President’s chief foreign affairs adviser.