To mark its fifth anniversary, Stephen E. Flynn, CFR’s leading national security expert, evaluates the general performance of the Office of Homeland Security.

Backgrounder: Experts say more should be done to reduce risk on both passenger and freight rail.

Technology plays an increasing role in Homeland Security efforts, spawning a growing U.S.industry for everything from biometrics to cargo screening at ports.

The air travel system remains one of the most high-profile targets for terrorists. This backgrounder examines efforts to improve aviation security since the 9/11 attacks.