Problems with the National Nuclear Security Administration’s nuclear stockpile surveillance program:

Critical tests on eight of the nine weapons in the U.S. stockpile were not done in 2005, the investigators found.

As a result, the nation’s military leadership “lacks vital information about the reliability of the stockpile,” the investigators found.

“I begin to worry,” said Ralph Levine, a retired federal official who until recently worked on the program. “If we ever had to use these things, would they in fact work?”

The investigation, released Thursday, is the latest from the Department of Energy’s Office of Inspector General, an independent oversight team within the agency that has repeatedly criticized the test program.

It echoes concerns Levine raised internally in a series of reports and memoranda beginning in 2002. Levine, who was based at the National Nuclear Security Administration’s Albuquerque office, retired in January.