U.S. foreign and defense policy is a complex web of institutions, players, and historical context. The President, State Department, and Department of Defense lead efforts to protect American interests abroad, while Congress provides oversight and funding. Constitutional powers shape the balance between executive and legislative branches. From the Monroe Doctrine to the Cold War and beyond, U.S. foreign policy has evolved with global events. Today, challenges include terrorism, nuclear proliferation, and rising powers like China. The U.S. uses diplomacy, economic tools, and military force to pursue its goals and maintain global influence.