The Department of
Homeland Security released the speech delivered by Secretary Michael Chertoff at the Center for Risk and Economic Analysis of Terrorism Events in Los Angeles. Among other things, he stated that the three basic principles of port security are partnership, risk management, and a layered approach to security. He pointed out that every shipment of cargo to the United States (100%) is currently screened. Those found to present a risk are then scanned.
Source: HK Law