WHEN a nation seeking to protect itself finds diplomacy, war, and foreign intelligence gathering insufficient, it can undertake three other types of activities to defend itself. It can control the movement of potential terrorists entering the country or traveling within it; it can capture or neutralize terrorist plotters within its borders; and when all else fails, it can mitigate damage from terrorist attacks. These three activities—access control, law enforcement, and disaster mitigation— comprise the essentials of homeland security. Congress and the Bush administration have consolidated many federal efforts to accomplish these three tasks in the Department of Homeland Security (DHS). In so doing they hope to protect the nation from future terrorist attacks.