United States Department of Homeland Security

The United States Department of Homeland Security (DHS) was created in response to the catastrophic failures of communication, coordination, and information-sharing within the U.S. federal government that contributed to the terror attacks of September 11, 2001. In a bid to create an agency that would protect the country from everything from natural disasters to hostile attacks, DHS incorporated the functions of multiple government agencies, including:

• U.S. Customs and Border Protection (CBP)
• U.S. Immigration and Customs Enforcement (ICE)
• Federal Emergency Management Agency (FEMA)
• Transportation Security Administration (TSA)
• U.S. Secret Service
• U.S. Coast Guard

The consolidation of, in all, 22 federal agencies made DHS the third-largest department in the U.S. government, behind the Departments of Defense and Veterans Affairs. As of 2026 DHS employed more than 260,000 workers.

DHS origin and mission

The DHS had its origins in the Office of Homeland Security, created in October 2001 by an executive order from U.S. Pres. George W. Bush. On November 25, 2002, Bush signed into law the Homeland Security Act, which established the Department of Homeland Security. Bush appointed former Pennsylvania governor Tom Ridge as the first secretary of homeland security.

Discover how ordinary objects work, and expand your understanding of the familiar.

SIGN UP

" height="20" alt="HEW Logo">

Thank you for signing up!"

Back to homepage

By clicking "Sign Up", you consent to the Britannica Privacy Policy and Terms of Use.

The department has identified six mission areas that guide its activities:

• Combating terrorism and threats to homeland security
• Securing U.S. borders
• Securing U.S. cyberspace and critical infrastructure
• Preserving the country’s economic security
• Strengthening the country’s preparedness and resilience capabilities
• Advocating for the workforce and operations of DHS

Impact on daily life

The creation of DHS and the new tactics used to protect the homeland brought changes, big and small, to American life. Air travel changed dramatically as airports increased their security requirements and screenings, restricting who had access to departure and arrival gates and limiting what people could carry onto an airplane. (For anyone born after 9/11, however, these changes are just the norm.)

Homeland Security Heads

• Tom Ridge (2003–05)
• Michael Chertoff (2005–09)
• Janet Napolitano (2009–13)
• Jeh Charles Johnson (2013–17)
• John F. Kelly (2017)
• Kirstjen M. Nielsen (2017–19)
• Alejandro Mayorkas (2021–25)
• Kristi Noem (2025– 2026)

The mandate of DHS to control U.S. borders, long a contentious, partisan political battle, has led to various approaches to illegal immigration. For example, while Pres. Barack Obama’s administration avoided deporting children who entered the country without documentation, his administration deported some three million individuals without legal status, compared with about two million during the George W. Bush administration. During the administrations of Pres. Donald Trump, DHS enforced selective bans on individuals from certain foreign countries, oversaw the partial construction of a wall along the southern U.S. border with Mexico, and executed mass deportations of immigrants living in the U.S. without proper documentation.

DHS also coordinates responses to cyberattacks and natural or human-caused disasters. The Federal Emergency Management Agency (FEMA) provides aid to states that experience severe flooding, storms, wildfires, earthquakes, and serious industrial or municipal accidents. States must request FEMA’s help before the agency can intervene. DHS works to prevent and respond to cyberattacks from individuals or nation-states on the U.S. economy, military, and energy infrastructure. Part of this effort involves the Electronic Surveillance System, used in criminal or intelligence investigations to collect data from targeted cell phones, computers, social media sites, and security cameras. Modern digital surveillance also includes facial recognition software and artificial intelligence-assisted programs that aid in border security, criminal investigations, and counterterrorism activities.

Explore Britannica Premium!

The trusted destination for professionals, college students, and lifelong learners.

SUBSCRIBE

Controversies

The Department of Homeland Security has been a lightning rod for controversy since its inception. In the immediate aftermath of 9/11, DHS implemented programs that, while intended to track down terrorists, had profound negative impacts on civil liberties. This included the use of technology and human intelligence to assess possible terror threats by accessing data from medical and social service providers as well as telephone and Internet logs.

In 2005 FEMA’s lack of preparedness and failure to provide a meaningful response in the aftermath of Hurricanes Katrina and Rita along the Gulf Coast drew heavy criticism from the public and Congress. In the wake of that failure, Congress implemented sweeping changes to FEMA, including a requirement that its director have experience in emergency management, although that has not always been the case.

The greatest controversy, however, has centered on border security. Since 2017 the deportation of immigrants has often involved a lack of coordination between federal and state authorities. Calls to “abolish ICE” gained traction in 2018 as the Trump administration enacted its family separation policy. (It was actually CBP that implemented family separation.) During the second Trump administration, federal agents from ICE and CBP conducted raids on cities including Chicago, Los Angeles, and Portland, Oregon, as well as opening a detention facility in Florida known as “Alligator Alcatraz.”

In late 2025 and early 2026 DHS, under the direction of Secretary Kristi Noem, initiated a massive immigration enforcement action in Minneapolis, Minnesota. Thousands of federal agents—many wearing masks, which DHS said was for their own protection—descended on the city and were met with protesters in the streets. Over the course of a little more than two weeks, two U.S. citizens, Renee Good and Alex Pretti, were shot and killed by federal officers. The government’s reaction to the deaths, including Noem and other officials labeling Good and Pretti “domestic terrorists,” led to protests around the country and the ultimate replacement of CBP official Gregory Bovino, who was overseeing the operation in Minneapolis, with border czar Tom Homan.

In the wake of the crisis, Congress threatened to withhold government funding for DHS unless there were changes to the management of federal agents. When, in February 2026, no agreement could be reached, funding lapsed for the department creating a partial government shutdown. Much of the department’s government employees, including TSA agents, continued working, without pay, as they did during the government record-long shutdown in the fall of 2025. As the 2026 partial government shutdown continued, travelers faced long lines at airports as fewer TSA agents, unable to work without pay, reported for duty. On April 30, 2026, the House of Representatives passed a temporary funding bill that would pay for most Homeland Security services through September 30,

In March 2026, Trump fired Noem after she was grilled by Democrats and Republicans in Congressional hearings. He named Oklahoma Republican Sen. Markwayne Mullin to succeed her.