"The nation's air, land, and marine transportation systems are designed for accessibility and efficiency, two characteristics that make them highly vulnerable to terrorist attack. While hardening the transportation sector from terrorist attack is difficult, measures can be taken to deter terrorists. The dilemma facing Congress is how best to construct and finance a system of deterrence, protection, and response that effectively reduces the possibility and consequences of another terrorist attack without unduly interfering with travel, commerce, and civil liberties. […] Existing law mandates the scanning of all U.S.-bound maritime containers with non-intrusive inspection equipment at overseas ports of loading by July 2012. This deadline is unlikely to be met, as foreign countries object to the costs of this screening and are dubious of the benefits. If Congress considers maritime security, it may examine the usefulness of this mandate, as well as the threat posed by the many small craft that populate commercial port areas and progress toward establishing harbor interagency operational centers."
CRS Report for Congress, RL33512