U.S. electrical grid penetrated by spies, hackers, or something unfathomably more terrible (update: China responds)

The Wall Street Journal has reported that the electricity grid in the United States has been infiltrated by "cyperspies," in an attempt to map the infrastructure, leaving behind software that could pose potential threats in times of crisis. Quoting anonymous "current and former" national security officials, the report claims that the spies, hailing from China, Russia, and "other countries" have not attempted to do any damage, but that they could, and that these types of intrusions are on the rise. Officials are of course worried about the potential implications of such penetrations, noting that much of our infrastructure, including nuclear power plants and financial institutions, are at risk. Unfortunately for the WSJ and its Cold War-era headline, the article goes on to state that it's not really possible to know whether a particular attack is "government sponsored," or just the work of regular old hackers from those regions running amok in cyberspace. Additionally, spokespeople from the Russian and Chinese Embassies vehemently deny their respective governments involvement in any such work. The Wall Street Journal, of course, fails to point out the most obvious of explanations: it's aliens.

Update: China has officially responded to the report. From a WSJ blog post:

"The intrusion doesn't exist at all," Chinese Foreign Ministry spokeswoman Jiang Yu said at a regular press conference. "We hope that the concerned media will prudently deal with some groundless remarks, especially those concerning accusations against China."

"I have also noticed that the U.S. White House had denied the media reports," she said.