Which department is responsible for the nation’s foreign affairs?

The Department of State is responsible for the nation's foreign affairs, thereby managing relationships with other countries and overseeing diplomacy. It handles a wide array of tasks including negotiating treaties, representing the U.S. in international organizations, and managing the issuance of visas for foreign visitors. The Department of State, led by the Secretary of State, plays a crucial role in shaping and implementing the nation's foreign policy, making it the primary agency in charge of diplomatic engagements and international relations.

Other departments, while they may touch upon foreign affairs in certain contexts, do not hold the primary responsibility for them. For instance, the Department of Defense focuses on military and defense issues, the Department of Justice deals with legal matters and law enforcement, and the Department of Commerce primarily concerns itself with economic interests and trade, rather than direct diplomatic functions. Each plays a supportive or related role, but the central authority on foreign affairs lies explicitly with the Department of State.