The U.S. government responds to scores of disasters each year in coordination with foreign, state, and local partners, but more frequent and severe storms, fires, and floods are straining resources.

The European Union has navigated a thicket of external and internal crises in recent years, including mass migration and Brexit. What are the union’s core institutions, and what roles do they play?

The separation of powers has spawned a great deal of debate over the roles of the president and Congress in foreign affairs, as well as over the limits on their respective authorities, explains this …