Personal data belonging to 134,386 current and former sailors in the U.S. Navy has been compromised, the Navy said on Wednesday.
It wasn't immediately clear when the hack took place, but the Navy is pointing the finger at a compromised laptop belonging to a contractor as the source of the data breach.
In a statement, the Navy said it was notified by Hewlett Packard Enterprise Services that a laptop belonging to one of its employees was compromised. That employee, the Navy said, was working in support of a Navy contract.
"The Navy takes this incident extremely seriously -- this is a matter of trust for our Sailors," said Chief of Naval Personnel Vice Adm. Robert Burke. "We are in the early stages of investigating and are working quickly to identify and take care of those affected by this breach."
A Navy official told ABC News that the breach was believed to only include social security numbers and names.
The official said that the contract with HPES was for a program known as Career Waypoints that the Navy uses for sailors to reenlist or apply for new Navy jobs.
According to the Navy Times, an initial investigation has not uncovered evidence that the data has been used in a malicious manner.
Affected sailors will be notified of the breach by email, letter and phone, the Navy said.
In an emailed statement, Thomas Wat Brandt, a spokesman for Hewlett Packard Enterprise, told ABC News: "The security and privacy of our clients is a top priority for Hewlett Packard Enterprise (HPE). This event has been reported to the Navy and because this is an ongoing investigation, HPE will not be commenting further out of respect for the privacy of our Navy personnel."
The scope of the data breach pales in comparison to the massive cyberattack on the federal government's Office of Personal Management that took place in 2015.
That attack -- which Chinese hackers are believed to have been behind -- saw personal data associated with more than 22 million people inside and outside of government stolen.
ABC News' Lucien Bruggeman contributed to this report from Washington.