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What is the Department of Homeland Security?

Updated: Aug 01, 2023  | Tags: Customs and Border Protection, Department of Homeland Security

The Department of Homeland Security (DHS) plays a pivotal role in ensuring the safety and security of the United States. Established in response to the 9/11 terrorist attacks, its mission encompasses a broad range of responsibilities intended to safeguard the country against diverse threats. This article explores the history, purpose, and functions of this key federal department.

History of the Department of Homeland Security

The creation of the DHS was largely a reaction to the terrorist attacks that occurred on September 11, 2001. Prior to this event, functions that are now within the remit of the DHS were spread across many different federal agencies.

The Homeland Security Act of 2002 led to the largest U.S. government reorganization since the establishment of the Department of Defense in 1947. It saw the amalgamation of 22 different federal departments and agencies into a single, unified department.

Purpose of the Department of Homeland Security

The overarching purpose of the DHS is to protect the United States and its territories from threats and enhance the nation's resilience against potential catastrophes. Its primary responsibilities encompass anti-terrorism, border security, immigration and customs, cybersecurity, and disaster prevention and management.

The mission statement of the DHS clearly encapsulates this purpose: "With honor and integrity, we will safeguard the American people, our homeland, and our values."

Functions of the Department of Homeland Security

The DHS fulfills its mission through a variety of subordinate agencies, each with its unique responsibilities and functions. Each of these agencies is listed and summarized below:a

Management Directorate (MGMT)

The Management Directorate is entrusted with the provision of administrative support services across the department, and supervises all auxiliary operations, such as: IT services, budgetary and financial management, procurement and acquisition, human resources, security, and administrative services. The Under Secretary establishes a comprehensive management framework for the Department, aimed at delivering efficient customer services. This structure also focuses on eliminating duplications and trimming support costs, thereby enhancing the effectiveness and efficiency of the Department's unified operations.

U.S. Customs and Border Protection (CBP)

As the largest federal law enforcement body under the United States Department of Homeland Security, the United States Customs and Border Protection (CBP) serves as the nation's primary organization for border control. Its key responsibilities include the oversight and facilitation of international commerce, collection of import duties, and enforcement of various U.S. laws encompassing trade, customs, and immigration. CBP is recognized as one of the most extensive law enforcement agencies across the United States. The ESTA also falls directly under the remit of CBP.

U.S. Immigration and Customs Enforcement (ICE)

ICE enforces federal laws related to border control, customs, trade, and immigration in order to promote homeland security and public safety.

Transportation Security Administration (TSA)

The TSA ensures the security of travelers within the United States. Its responsibilities include securing the nation's airports, screening all commercial airline passengers and baggage, and implementing regulations to secure U.S. highways, railroads, ports, and mass transit systems.

U.S. Citizenship and Immigration Services (USCIS)

U.S. Citizenship and Immigration Services (USCIS) operates as a part of the United States Department of Homeland Security (DHS), responsible for overseeing the nation's immigration and naturalization procedures. Much like the defunct INS, USCIS undertakes the processing and adjudication of a range of immigration matters. This includes overseeing applications for work visas, asylum, and citizenship. Beyond these responsibilities, the agency has the official mandate to ensure national security, manage immigration case backlogs, and strive for increased efficiency.

Federal Emergency Management Agency (FEMA)

FEMA's primary responsibilities involve coordinating the response to disasters that occur within the United States and overwhelm the resources of local and state authorities.

U.S. Coast Guard

As a branch of the military, the U.S. Coast Guard is involved in maritime security, search and rescue, and law enforcement.

Cybersecurity and Infrastructure Security Agency (CISA)

CISA leads efforts to protect and enhance the resilience of the nation's physical and cyber infrastructure.

Science and Technology Directorate (S&T)

The Science and Technology Directorate (S&T) forms an integral part of the United States Department of Homeland Security. As the department's primary research and development branch, DHS-S&T plays a critical role in the nation's security operations. The leadership of the Science and Technology Directorate falls under the jurisdiction of the Under Secretary of Homeland Security for Science and Technology, a position appointed by the U.S. President and confirmed by the U.S. Senate.

Office of Intelligence and Analysis (I&A)

The Office of Intelligence and Analysis (I&A) operates as the non-military intelligence branch of the United States Department of Homeland Security, working in tandem with Coast Guard Intelligence as the department's two statutory members of the U.S. Intelligence Community (IC). Unique among IC members, I&A's role includes delivering intelligence to State, Local, Tribal, and Territorial (SLTT) governments and private organizations, as well as synthesizing national intelligence reports using information sourced from SLTT entities.

United States Secret Service (USSS)

The United States Secret Service is a federal law enforcement agency under the Department of Homeland Security. It has two primary missions: protecting national leaders and safeguarding the nation's financial infrastructure and payment systems. Protection duties extend to the President, Vice President, their immediate families, former presidents, and visiting foreign dignitaries. The Secret Service also plans security for major national events, such as inaugurations and international summits.

Domestic Nuclear Detection Office (DNDO)

The DNDO serves as a coordinator for federal initiatives in the United States that aim to detect and safeguard against nuclear and radiological terrorism threats within the country. Leveraging its interagency resources, the DNDO orchestrates the creation of the global nuclear detection architecture, the strategic framework that guides the nuclear detection endeavors of the U.S. government. DNDO is actively involved in researching, developing, testing, and evaluating nuclear and radiological detection technologies. Moreover, it holds the responsibility for procurement of the technology systems required for executing the domestic components of the global nuclear detection architecture. Beyond these roles, DNDO delivers standardized threat assessments and technical support, and offers training as well as response protocols to federal and non-federal partners.


Since its establishment, the Department of Homeland Security has played an increasingly integral role in maintaining the safety and security of the United States. By understanding its history, purpose, and functions, we can gain a deeper insight into the multifaceted efforts to protect the American people, the homeland, and the country's values. Its broad mandate reflects the complexity of modern threats, encompassing everything from immigration and border security to disaster management and cybersecurity. In all these areas, the DHS remains at the forefront of defending the nation's safety and security.