In American national security policy, homeland security is "the national effort to ensure a homeland that is safe, secure, and resilient against terrorism and other hazards where American interests, aspirations, and ways of life can thrive" to the "national effort to prevent terrorist attacks within the United States, reduce the vulnerability of the U.S. to terrorism, and minimize the damage from attacks that do occur." According to an official work published by the Congressional Research Service in 2013, the "Homeland security" term's definition has varied over time.
Homeland security is not constrained to terrorist incidents. Terrorism is violent, criminal acts committed by individuals and/or groups to further ideological goals stemming from influences, such as those of a political, religious, social, racial, or environmental nature. Within the US, an all-hazards approach exists regarding homeland security endeavors. In this sense, homeland security encompasses both natural disasters and man-made events. Thus, the domain of homeland security must accommodate a plethora of situations and scenarios, ranging from natural disasters (e.g., Hurricane Katrina, Irma) to acts of terrorism (e.g., Boston Marathon bombing, September 11 attacks).