There are a number of countries that we see cyber-attacks emanating from. And, again, they can be just individuals who are located in the country. But three that I think are of special concern would be Iran, would be Russia, and China.

The last thing the Department of Homeland Security is about is infringing on anybody's constitutionally protected rights.

Bob Mueller for the FBI, myself, met with a particular group of executives that have major roles in the so-called ISPs, the Internet service providers, what they could possibly do. We have met with leaders in private industry in terms of the core critical infrastructure of the country as to what they can possibly do with cyber-attacks.

All images generated by imaging technology are viewed in a walled-off location not visible to the public. The officer assisting the passenger never sees the image, and the officer viewing the image never interacts with the passenger. The imaging technology that we use cannot store, export, print or transmit images.

It's always been government's role to protect the security of the nation. And cyber-attacks is a security issue, from our perspective. And it's a security issue of particular concern with respect to the nation's core critical infrastructure, the infrastructure everyone relies on, the energy sector, the telecommunications sector, the banking sector.

It drove home, personally, the value of early detection and education and intervention.

So not only do we need to deal with threats as they emerge, we have to be thinking in anticipation of future threats, and the things we do have to be things that enable the system to continue to work.