From the Document: "Initially, homeland security was largely seen as counterterrorism activities. Today, homeland security is a broad and complex network of interrelated issues, in policymaking terms. For example, in its executive summary, the Quadrennial Homeland Security Review issued in 2014 delineated the missions of the homeland security enterprise as follows: prevent terrorism and enhance security; secure and manage the borders; enforce and administer immigration laws; safeguard and secure cyberspace; and strengthen national preparedness and resilience."
CRS Report for Congress, R45701
Congressional Research Service: https://crsreports.congress.gov/