Strategy Page explains why the much-discussed threat of terrorists smuggling in weapons of mass destruction using the ubiquitous shipping container has not actually happened:
A decade ago there was much talk about how vulnerable the United States was to a terror attack via shipping container. It never happened. It’s also unlikely because of the large number of variables the terrorists face. The problems associated with using cargo containers to move a nuclear or conventional bomb are manifold. The big problem is that these containers often don’t arrive right on schedule. Sometimes the ship breaks down or encounters bad weather. This last event leads to thousands of containers a year falling off cargo ships and going to the bottom with their cargo. Sometimes containers get lost “in the system.” More frequently containers get robbed or opened by mistake. Customs officials open a small percentage (this varies by port) for inspection. Another problem, whether the bomb goes off or not, is the fact that containers have to have documentation like bills of lading and such. These can be faked, but the problem is that a paper trail is being created and that can lead to terrorists getting arrested. All containers must officially belong to someone, they are tracked and any that aren’t being tracked tend to get noticed. Many countries do scrutinize containers coming from certain countries in an attempt to catch people smuggling drugs or arms. Large bombs, be they nuclear or conventional, are relatively fragile and may not survive (in working condition) the punishment received during a long sea voyage. If all that weren’t enough to make terrorists nervous, container ships can be delayed when trying to enter a port because of congestion. This can delay arrival by days, or even weeks.