Updated

Former Federal Energy Regulatory Commission chairman Jon Wellinghoff says he believes an April attack on Silicon Valley's phone lines and power grid was terrorism.

Wellinghoff, who was in office during the incident, said he reached his conclusion after consulting with Defense Department experts to review the attack that involved snipping AT&T fiber-optic lines to knock out phone and 911 service. In addition, shots were fired into a PG&E substation, causing outages.

Wellinghoff made the statement on Wednesday to The Associated Press. His comments were initially reported by The Wall Street Journal.

The FBI is still investigating but says there is no indication it was an act of terrorism.

Wellinghoff says he is speaking out because he's concerned the grid is not being adequately protected.