In probably the most severe warning of cyberwar, Washington Post columnist Robert J. Samuelson says he'd like to abolish the Internet.

Sure, we can watch YouTube and listen to music through iTunes, but the Internet isn't a symbol of progress, he says.

"Just the opposite. We would be better off without it," Samuelson writes, saying its benefits are relatively modest compared to previous technologies like electricity, cars or antibiotics.

Declassified: ‘Financial War’ Could Wipe Out 50% of Your Wealth

"The Internet's virtues are overstated, its vices understated. It’s a mixed blessing - and the mix may be moving against us."

Nations, terrorists or hackers can use the Internet to disrupt or destroy power grids, pipelines, communication and financial systems, businesses, railroads and airlines, and databases.

"The list runs on. So much depends on the Internet that its vulnerability to sabotage invites doomsday visions of the breakdown of order and trust," he warns.

A Defense Science Board report to the Pentagon, he notes, warns that there would be "no electricity, money, communications, TV, radio or fuel (electrically pumped). In a short time, food and medicine distribution systems would be ineffective."

Plus, the report says hackers could hit the U.S. military hard, disarming weapons our directing them against our own troops.

Criminals are increasingly using the Internet for theft. For instance, thieves recently stole $45 million by hacking into databases of prepaid debit cards and then draining cash from ATMs.

Theft of trade secrets is another Internet risk. The cybersecurity firm Mandiant lists aerospace and defense, followed by energy and pharmaceuticals as the top targets for trade secrets.

In the past, most infrastructure systems like electricity grids were self-contained, using dedicated phone lines and private communications networks. Many have jumped on the Internet bandwagon, apparently underestimating the risks.

One attack infected about 30,000 computers of Aramco, Saudi Arabia's oil company.

Experts agree the U.S. needs to improve its defense against cyberattacks, but they disagree over what sectors deserve the most attention.

The common warnings about cyberattacks on electrical systems are overblown, writes Rand Corp. analyst Mark Sparkman in an article for CNN.

Many areas have routinely gone without electricity and water for days but recover afterwards, says Sparkman, a former senior officer with the CIA’s National Clandestine Service.

"Want real chaos? Destroy confidence in the banking system (or even a part of it), and just stand back and watch."

"The banking system is built on trust. It’s slow to establish and fragile to keep. That trust must be fiercely protected."

Declassified: ‘Financial War’ Could Wipe Out 50% of Your Wealth