Backup tapes containing unencrypted personal information of nearly five million current and former US soldiers were stolen from a defence contractor.
The data on the backup tapes belonged to Tricare, a US health benefits provider for military personnel, retirees and their dependents.
It was swiped from a car owned by an employee of Science Applications International Corp. (SAIC), a high-tech defense contractor meant to safeguard the data.
The stolen records affect 4.9 million people who, from 1992 to Sept. 7 of this year, sought care at military treatment facilities in Texas.
The data included social security and phone numbers, addresses and clinical information including notes, lab test reports and prescription information.
The high tech defence contractor said the data was unencrypted because it lacked the capability to do to in line with US Government standards.
It said retrieval of the data was unlikely because doing so "requires knowledge of and access to specific hardware and software, and knowledge of the system and data structure".
"The government was seeking a compliant encryption solution that would work with the operating system when the backup tapes were taken," the company said.
It took Tricare two weeks to reported 14 Septemeber theft.
"We did not want to raise undue alarm in our beneficiaries and so wanted to determine the degree of risk this data loss represented before making notifications."
Representatives from SAIC and Tricare did not immediately respond to a request for comment.