United States Department of Homeland Security

U.S. Department of Homeland Security logo

Overview of the Department

The Department of Homeland Security (DHS) is a crucial federal agency in the United States responsible for safeguarding the nation from various threats and ensuring the safety and security of its citizens. Established in response to the 9/11 terrorist attacks, the DHS officially began operations on March 1, 2003. Its primary mission is to protect the United States from various threats, including terrorism, natural disasters, and other emergencies.

With over 200,000 employees, DHS is the third-largest government cabinet department after the Departments of Defense and Veterans Affairs. Homeland security policy is coordinated at the White House by the Homeland Security Council. Other agencies with significant homeland security responsibilities include the Department of Health and Human Services, the United States Department of Justice, and the Department of Energy.

The creation of the Department constituted the biggest government reorganization in American history and the most substantial reorganization of federal agencies since the National Security Act of 1947, which placed the different military departments under a secretary of defense and created the National Security Council and Central Intelligence Agency. Also, the DHS constitutes the most diverse merger of federal functions and responsibilities, incorporating 22 government agencies into one organization.

Key Components and Responsibilities

Key components and responsibilities of the Department of Homeland Security include:

Preventing Terrorism

DHS plays a vital role in preventing terrorist attacks within the United States. This involves intelligence gathering, risk analysis, and collaboration with other federal, state, local, tribal, and territorial agencies.

Border Security and Immigration Enforcement

The DHS oversees the enforcement of immigration laws and works to secure the nation’s borders. This includes managing customs and border protection, immigration and customs enforcement, and ensuring the integrity of the immigration system.

Emergency Response and Recovery

In natural disasters, man-made emergencies, or other crises, DHS coordinates and supports federal, state, and local response efforts. This involves providing resources, personnel, and expertise to help affected communities recover.


With the increasing threat of cyber attacks, DHS is protecting the nation’s critical infrastructure, information systems, and networks. The agency collaborates with public and private sector partners to enhance cybersecurity measures.

Transportation Security

DHS is responsible for ensuring the security of the nation’s transportation systems, including airports, seaports, and highways. This involves implementing measures to prevent terrorist attacks and protect the traveling public.

Critical Infrastructure Protection

The DHS works to enhance the resilience and security of critical infrastructure, such as energy, water, and telecommunications systems, to mitigate the impact of potential threats and disruptions.

Intelligence and Analysis

DHS gathers, analyzes, and shares intelligence on threats against the United States. This involves collaboration with various intelligence agencies to assess and respond to emerging risks.

Science and Technology

The DHS invests in research and development to advance technologies that can enhance the capabilities of homeland security operations. This includes developing tools for detection, surveillance, and response.

The Department of Homeland Security is led by the Secretary of Homeland Security, a member of the President’s Cabinet. The agency operates through numerous sub-agencies, including the Federal Emergency Management Agency (FEMA), Transportation Security Administration (TSA), Customs and Border Protection (CBP), Immigration and Customs Enforcement (ICE), and the United States Secret Service, among others. The DHS plays a critical role in ensuring the safety and resilience of the United States in an ever-evolving threat landscape.

U.S. Department of Homeland Security Color Code Threat Advisory System

In March 2002, the U.S. Department of Homeland Security Chief Tom Ridge unveiled a new color-coded threat advisory system for the United States. The idea was to create a way to convey the risk of terrorist attacks to federal, state, and local authorities and the American people. The coded warning system has five levels associated with a suggested protective measure and will trigger specific actions by federal agencies and local law enforcement.

The Homeland Security Color Code Threat Advisory System was recently discontinued. Information on the new advisory system is listed below:

About the Advisory System

The Department of Homeland Security Advisory System guides our protective measures when specific information about a particular sector or geographic region is received. It combines threat information with vulnerability assessments and provides communications to public safety officials and the public.

  • Threat Advisories contain actionable information about an incident involving, or a threat targeting, critical national network infrastructures, or key assets.
  • Homeland Security Information Bulletins communicate information of interest to the nation’s critical infrastructures that do not meet warning message timeliness, specificity, or significance thresholds.
  • The color-coded Threat Level System is used to communicate with public safety officials and the public through a threat-based, color-coded system so that protective measures can be implemented to reduce the likelihood or impact of an attack.

More Information

For more information and the current terrorism threat level, please visit the Department of Homeland Security website.

Michael Kissiah is the owner of Brandy Lane Publishing, LLC, which owns and operates a small portfolio of websites, including eInvestigator.com. Michael created eInvestigator.com more than 20 years ago after working as a private investigator in the state of Florida. Since that time, he has become an expert at how to find information online and has written over 1000 articles on topics related to the investigation industry. In addition, he is the author of the "Private Investigator Licensing Handbook", available at Amazon.com.


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