Which governmental agency serves as the outermost layer of the U.S. aviation security system?

The Department of Homeland Security (DHS) serves as the outermost layer of the U.S. aviation security system because it is responsible for overseeing and coordinating the nation's security efforts regarding transportation, including aviation. Established in response to the September 11 attacks, DHS integrates multiple agencies to protect the United States from threats, ensuring a cohesive approach to security across various domains.

DHS has authority over broader security policies and frameworks that encompass aviation security among various other areas, including border protection, emergency management, and immigration enforcement. This central role allows it to collaborate with other agencies like the Transportation Security Administration, which handles the implementation of security measures at airports, and the Federal Aviation Administration, which focuses on regulating civil aviation safety. The FBI also plays a role in investigating any criminal activities related to aviation security, but it operates in a supportive capacity relative to the overarching security strategy established by DHS.

Thus, while other agencies contribute significantly to specific facets of aviation security, DHS is positioned as the overarching authority that integrates and directs efforts to protect the aviation sector within the national security framework.