U.S. flag

An official website of the United States government

Government Website

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Safely connect using HTTPS

Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


  1. Home
  2. News
  3. Publications Library
  4. Do Business with DHS
  5. Preventing Terrorism and Enhancing Security

Preventing Terrorism and Enhancing Security

The Department of Homeland Security (DHS) and its many partners across the federal government, public and private sectors, and communities across the country and around the world have worked since 9/11 to build a new homeland security enterprise to better mitigate and defend against dynamic threats, minimize risks, and maximize the ability to respond and recover from attacks and disasters of all kinds. 

Together, these efforts have provided a strong foundation to protect communities from terrorism and other threats, while safeguarding the fundamental rights of all Americans. 

While threats persist, our nation is stronger than it was on 9/11, more prepared to confront evolving threats, and more resilient in the face of our continued challenges.

Read the Implementing 9/11 Commission Recommendations, Progress Report 2011.

Protecting the United States from terrorism is the founding mission of the Department of Homeland Security. While America is stronger and more resilient as a result of a strengthened homeland security enterprise, threats from terrorism persist and continue to evolve. Today's threats do not come from any one individual or group. They may originate in distant lands or local neighborhoods. They may be as simple as a home-made bomb or as sophisticated as a biological threat or coordinated cyber attack. More and more, state, local, and tribal law enforcement officers, as well as citizens, businesses, and communities are on the front lines of detection and prevention. Protecting the nation is a shared responsibility and everyone can contribute by staying informed and aware of the threats the country faces. Homeland security starts with hometown security—and we all have a role to play.

Building the Homeland Security Enterprise

  • Fusion Centers: DHS supports state and major urban area fusion centers through personnel, training, technical assistance, exercise support, security clearances, connectivity to federal systems, technology, and grant funding.
  • Nationwide Suspicious Activity Reporting Initiative: An administration effort to train state and local law enforcement to recognize behaviors and indicators related to terrorism, crime and other threats; standardize how those observations are documented and analyzed; and enhance the sharing of those reports with law enforcement across the country.
  • Grant Funding: Since fiscal year 2003, DHS has awarded more than $31 billion in preparedness grant funding based on risk to build and sustain targeted capabilities to prevent, protect against, respond to, and recover from threats or acts of terrorism.

Preventing Terrorist Travel and Improving Passenger Screening

  • Advance Passenger Information and Passenger Name Record Data: To identify high-risk travelers and facilitate legitimate travel, DHS requires airlines flying to the United States to provide Advance Passenger Information and Passenger Name Record (PNR) Data prior to departure. During 2008 and 2009, PNR helped the United States identify individuals with potential ties to terrorism in more than 3,000 cases, and in fiscal year 2010, approximately one quarter of those individuals denied entry to the United States for having ties to terrorism were initially identified through the analysis of PNR.
  • Visa Security Program: Through the Visa Security Program (VSP), with concurrence from the Department of State, ICE deploys trained special agents overseas to high-risk visa activity posts in order to identify potential terrorist and criminal threats before they reach the United States. The VSP is currently deployed to 19 posts in 15 countries.
  • Pre-Departure Vetting: DHS has strengthened its in-bound targeting operations to identify high-risk travelers who are likely to be inadmissible to the United States and to recommend to commercial carriers that those individuals not be permitted to board a commercial aircraft through its Pre-Departure program. Since 2010, CBP has identified over 2,800 passengers who would likely have been found inadmissible upon arrival to the United States.
  • Secure Flight: Fulfilling a key 9/11 Commission recommendation, DHS fully implemented Secure Flight in 2010, in which TSA prescreens 100 percent of passengers on flights flying to, from, or within the United States against government watchlists before travelers receive their boarding passes. Prior to Secure Flight, airlines were responsible for checking passengers against watchlists. Through Secure Flight, TSA now vets over 14 million passengers weekly.
  • Enhanced Explosives Screening: Prior to 9/11, limited federal security requirements existed for cargo or baggage screening. Today, TSA screens 100 percent of all checked and carry-on baggage for explosives. Through the Recovery Act and annual appropriations, TSA has accelerated the deployment of new technologies to detect the next generation of threats, including Advanced Imaging Technology units, Explosive Detection Systems, Explosives Trace Detection units, Advanced Technology X-Ray systems, and Bottled Liquid Scanners.

Strengthening Surface Transportation Security

  • Visible Intermodal Prevention and Response Teams: TSA has 25 multi-modal Visible Intermodal Prevention and Response (VIPR) Teams working in transportation sectors across the country to prevent or disrupt potential terrorist planning activities. Since the VIPR program was created in 2008, there have been over 17,700 operations performed.
  • Baseline Surface Transportation Security Assessments: Since 2006, TSA has completed more than 190 Baseline Assessments for Security Enhancement for transit, which provides a comprehensive assessment of security programs in critical transit systems.

Strengthening Global Supply Chain Security

  • Air Cargo Screening: Fulfilling a requirement of the 9/11 Act, 100 percent of all cargo transported on passenger aircraft that depart U.S. airports is now screened commensurate with screening of passenger checked baggage and 100 percent of high risk cargo on international flights bound for the United States is screened.
  • Container Security Initiative: The Container Security Initiative (CSI), currently operational in 58 foreign seaports in 32 countries, identifies and screens U.S.-bound maritime containers that pose a potential risk.

Detecting and Preventing Biological, Radiological, and Nuclear Threats

  • Detection at Ports of Entry: DHS has deployed radiation detection technologies to seaports, land border ports, and mail facilities around the world. These systems scan 100 percent of all containerized cargo and personal vehicles arriving in the U.S. through land ports of entry, as well as over 99 percent of arriving sea containers.
  • State and Local Radiological Emergency Preparedness: DHS's Domestic Nuclear Detection Office has made radiological and nuclear detection training available to over 15,000 state and local officers and first responders.
  • BioWatch: The Department's BioWatch system is a federally-managed, locally-operated, nationwide bio-surveillance system designed to detect the intentional release of aerosolized biological agents.

Protecting Critical Infrastructure

  • Chemical Facility Anti-Terrorism Standards: DHS has implemented Chemical Facility Anti-Terrorism Standards to regulate security at high-risk chemical facilities. To date, approximately 4,500 facilities have been preliminarily identified as high-risk, resulting in the development and submission of Security Vulnerability Assessments.  
  • Critical Infrastructure Security Assessments: DHS has conducted more than 1,900 security surveys and 2,500 vulnerability assessments of the nation's critical infrastructure to identify potential vulnerabilities and provide recommendations on protective measures.
  • Training and Education: DHS has developed a variety of infrastructure protection training and educational tools for its partners at the state and local level. In total, more than 35,000 partners have taken risk mitigation training on a range of topics.

Read the Implementing 9/11 Commission Recommendations, Progress Report 2011

Last Updated: 12/21/2022
Was this page helpful?
This page was not helpful because the content