It's more the concept of not controlling what's crossing our borders and entering our ports, isn't it??
Do you really believe that it is possible to control every single thing crossing our borders? No way, not ever. We can try to control rampant illegal immigration and try to sniff out nuclear materials but beyond that - impossible.
At some point we have to individually accept responsibility for taking care of ourselves during changes in our environment. The "government" can only go so far and expectations of it providing complete security for us is a pipe dream and we all ought to get real.
Our ports are our borders, look at a map sometime.