"Today's threats are not limited to any one individual, group or ideology and are not defined nor contained by international borders. Terrorist tactics can be as simple as a homemade bomb and as sophisticated as a biological threat or a coordinated cyber attack. We have had success in thwarting numerous terrorist plots including the attempted bombings of the New York City subways and Times Square, foiled attacks against air cargo, and other attempts across the country. […] To continue to address these evolving threats, DHS employs risk-based, intelligence-driven operations to prevent terrorist attacks. Through a multi-layered detection system focusing on enhanced targeting and information sharing, DHS works to interdict threats and dangerous people at the earliest point possible. DHS also works closely with its Federal, State and local law enforcement partners on a wide range of critical homeland security issues in order to provide those on the frontlines with the tools they need to address threats in their communities. Strengthening homeland security also includes a significant international dimension. To most effectively carry out DHS's core missions - including preventing terrorism, securing our borders, and protecting cyberspace - we must partner with countries around the world. This work ranges from strengthening cargo, aviation, and supply chain security to joint investigations, information sharing, and science and technology cooperation. Through international collaboration, we not only enhance our ability to prevent terrorism and transnational crime, we also leverage the resources of our international partners to more efficiently and cost-effectively secure global trade and travel. Today, DHS works in more than 75 different countries, the third largest foreign footprint of any civilian U.S. Government agency, in order to address and respond to evolving threats before they reach our shores."
U.S. Dept. of Homeland Security: http://www.dhs.gov/