Attackers sever fiber-optic cables in San Francisco area, latest in a string

Trevor Hughes | USA TODAY

Show Caption Hide Caption FBI investigating string of attacks against Internet backbone in Calif. The FBI is investigating string of attacks against the Internet backbone in California, including one early Tuesday morning.

Someone deliberately severed two AT&T fiber optic cables in the Livermore, Calif., Monday night, the latest in a string of attacks against the Internet's privately run backbone.

AT&T is offering a $250,000 reward in connection with the latest attacks. AT&T's fiber optic network is legally considered a critical piece of the nation's Internet infrastructure, and any attackers are subject to both state and federal prosecution. The FBI already has an open investigation into 14 similar attacks on California Internet backbones since last summer.

Livermore is a San Francisco Bay Area suburb that's home to the Lawrence Livermore National Laboratory and many high-tech commuters.

"It's a serious matter and affects public safety at large," AT&T spokesman Jim Greer said Tuesday.

The high-capacity lines, which aren't much thicker than a pencil, carry vast amounts of data. Everything from phone calls to computer transactions, emails, and even the security cameras feeds watching the cables themselves travel down the plastic or glass fibers as pulses of light. The cables are the interstate highways of the information superhighway.

The FBI says whoever has been attacking the cables usually opens a underground vault, climbs inside and then cuts through the cables' protective metal conduit before severing the lines themselves.

"It's being taken very seriously by the FBI and our law enforcement partners," said Michele Ernst, a spokeswoman for the bureau's San Francisco field office.

Security experts say the attacks could be the work of a disgruntled employee or of terrorists probing the nation's infrastructure to see how long repairs take. FBI officials say it's possible whoever has been attacking the cables is dressed as a utility company employee.