Salt Lake City - Electrical problems have stalled the planned opening this fall of the nation's new $1.7 billion epicenter for fighting global cyber threats - a Utah data center filled with super-powered computers designed to store massive amounts of classified information.

The Army Corps of Engineers discovered the problems during tests ahead of the scheduled Oct. 1 opening of the center south of Salt Lake City, on a National Guard base, Corps spokeswoman Diedra Cordell said in an emailed statement.

The facility will be the National Security Agency's largest data storage center in the US, constantly using 65 megawatts of electricity - enough to power 33,000 houses. But what exactly will be happening there remains shrouded in mystery. There is no visible marker bearing the facility's name and operator, and the NSA has been tight-lipped about what they'll be doing there.

The Corps, which is in charge of construction, says experts are working to correct the electrical problems. Cordell did not provide details about the exact nature of the issue, or say if it has caused any major damage.

NSA spokeswoman Vanee Vines acknowledged the problems in an email but declined to provide any more information.

"The failures that occurred during testing have been mitigated," Vines said in a statement. "A project of this magnitude requires stringent management, oversight, and testing before the government accepts any building."

The problems were first reported by the Wall Street Journal.

NSA officials say the center will play a key role in the nation's effort to protect national security networks, and allow US authorities to monitor for potential cyber threats. The secrecy is necessary to protect classified information that is highly sought-after by foreign spies, said a former US intelligence official who spoke on condition of anonymity because the official was not authorized to discuss the program publicly.

Richard "Dickie" George, who retired from the NSA in 2011 after 40 years, says the facility isn't nearly as mysterious as some think. The center only holds data, with NSA agents elsewhere combing through the information to understand how terrorist groups operate and who plays what roles. George calls it no more than a "big file cabinet" out West.

The Army Corps also found an air flow problem with the generators that they are working to fix, Cordell said. The agency is working to complete its final inspection of the center before handing it over, she said.

NSA officials have said the agency chose the Utah location over 37 others because electricity is cheaper here, and because it was easier to buy enough land to build the center's long, squat buildings that span 1.5 million square feet. The center sits on a hill in Bluffdale, a community of about 8,000 people 25 miles south of Salt Lake City that is known for its rodeo and annual Old West Days.

The utility that powers the data center said it determined the electrical problems are the fault of the NSA data center and not the power grid. The utility's engineers did a detailed analysis of their systems during the times the NSA reported problems, said Rocky Mountain Power spokesman David Eskelsen.

"It's something internal to the NSA system," Eskelsen told The Associated Press.

James Bamford, the author of several books on the NSA who last year wrote about the Utah center in Wired magazine, said the problems sound very serious from what he read in the Wall Street Journal story.

The center has some standard servers, but most of it is extremely unique, state-of-the-art equipment that is expensive. It's not surprising to Bamford that they are encountering problems considering how much data they are trying to store and make available around the world via fiber-optic cables.

"There's never been a time in US history where they've tried to collect so much data in one place and then try to access it from other places on a cloud," Bamford said