The secure movement of a large portion of goods from one country to another is a task that can only be completed with cargo shipping containers. Every year, millions of such shipping containers are loaded onto boats that then make their way into the United States. These containers were only recognized as a potential threat to homeland security after the attacks on September 11, 2001. While actions have been taken to minimize the threat, cargo shipping containers remain to be a real danger. Only a small percentage of them are screened before they leave port.
In order to make cargo shipping container operations entirely safe, all containers have to be screened. This would entail screening thousands upon thousands of containers before they leave the port. With modern day demand, such a task is not feasible. United States Customs and Border Protection is in charge of ensuring the shipping containers are safe, but they have not had the technology to enact widespread changes. Thankfully, there are several organizations that have been working for years to help solve this problem.
For example, the Soreq Nuclear Research Center in Israel, for example, announced in 2010 that they could create a single machine to screen all cargo containers quickly, so as to not slow down production. The machine was predicted to be able to pass beams through the containers that could then be measured to determine what kind of material a shipping container is holding. Similar machines now exist in ports all over the world, but they are not used on all containers.
Different ports refuse to scan their cargo shipping containers for several reasons, none of which include the desire to conceal what exists inside. It is ultimately an issue of efficiency. Scanning every cargo shipping container takes up valuable time and is disruptive to production. Additionally, the existing scanners are not entirely effective. They are known to emit false positives at even the slightest hint of radiation (say, from bananas,) and some countries are even worried the scanning machines could affect cargo with radiation. Needless to say, there are several reasons for a port not to scan all shipping containers, which is the problem the United States now faces.
Overall, I want to stress the threat that these containers pose to United States Homeland Security, and the importance of finding a solution that ensures no threat is contained within a container while not slowing down production.