The challenge is to find the needle in the haystack. A weapon of mass destruction could be in one of the shipping containers. Many of the containers are associated with known importers and exporters - only 7,400 of the 400,000 importers account for over 80% of the value of imports to America.2 There's a pattern to their imports, and inspection might be targeted towards the containers from less-known sources.
However, through 2001, the inspection process occurred at the port of destination. A shipping container unloaded at Hampton Roads might be transported through Richmond before being examined as an official import at its destination "port." There's the potential for a terrorist to slip a weapon of mass destruction into such a container and trigger it far from Hampton Roads, before the container might be examined.3