Less than a decade ago, "60 Minutes" went to the Pentagon to do a story on something called information warfare, or cyberwar as some people called it. It involved using computers and the Internet as weapons.

Much of it was still theory, but we were told that before too long it might be possible for a hacker with a computer to disable critical infrastructure in a major city and disrupt essential services, steal millions of dollars from banks all over the world, infiltrate defense systems, extort millions from public companies, and even sabotage our weapons systems.

Today it's not only possible, all of that has actually happened. And there's a lot more we don't even know about.

It's why President Obama has made cyberwar defense a top national priority and why some people are already saying that the next big war is less likely to begin with a bang than with a blackout.

"Can you imagine your life without electric power?" Ret. Adm. Mike McConnell asked "60 Minutes" correspondent Steve Kroft...

Read more of "Cyber War: Sabotaging the System" at CBSNews.com.