Missing data not a security threat, Los Alamos says

"This in our view is not a major event and it's certainly not a breach of security," said Kevin Roark, spokesman for the New Mexico facility.

Roark said laboratory employees conducting an inventory of classified information could not locate the data storage device containing classified information. The storage device remained unaccounted for Thursday, and a federal review team is preparing to investigate, he added.

"It's our strong belief [it] was either destroyed or retasked, but the proper paperwork wasn't done to track its destruction or reuse," Roark said.

The laboratory said in a statement that the device was set to be destroyed in March as part of a plan to reduce what is called Classified Removable Electronic Media.

"An extensive laboratory-wide effort to reduce Classified Removable Electronic Media has resulted in a single accounting discrepancy. Based upon an initial review, this discrepancy in no way constitutes a compromise of national security," the statement said.

"The lab can spin it however they want," Danielle Brian, executive director of the Project on Government Oversight, a Washington-based watchdog group, told the AP. "Classified data is missing once again from Los Alamos." Rep. Tom Udall, D-N.M., issued a statement saying laboratory officials assured him that "the information does not contain nuclear weapons data."

The laboratory stopped work at its Nuclear Nonproliferation Division late last year after nine floppy disks and a large-capacity storage disk believed to contain some classified information were found to be missing.