More than 60,000 sensitive US military files have been found on a publicly accessible Amazon server by a security researcher.
The files contained passwords for US government systems and the security credentials of a senior engineer at defence contractor Booz Allen Hamilton (BAH).
They were discovered by Upguard analyst Chris Vickery.
In a statement, BAH said no classified data had been stored on the server.
"We have confirmed that none of those usernames and passwords could have been used to access classified information," the contractor added.
The files were connected to a project for the US National Geospatial-Intelligence Agency (NGA), which deals with satellite and drone surveillance imagery.
BAH said it believed the incident was the result of "an unintentional mistake".
"As soon as we learned of this mistake, we took action to secure the areas and alerted our client and began an investigation.
"Our client has said they've found no evidence that classified data was involved, and so far our forensics have indicated the same", the company said.
Mr Vickery told the BBC he found the data during "a routine search for publicly accessible Amazon [simple storage service] buckets".
"I wasn't very surprised at finding yet another publicly exposed bucket until I realised the data it contained was related to a government project".
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He emailed BAH's chief information security officer about the files on 24 May.
"When I hadn't heard back from him by the following day, I forwarded the same notification email to the NGA", he explained.
"The email went out at 10:33 PST (17.33 GMT) on 25 May. The bucket was secured at 10:42 PST.
"The fact that it was closed off nine minutes after I sent the 'escalated' email would be a very big coincidence indeed."
On 26 May, a US government agency contacted UpGuard to ask that it preserve all the data Mr Vickery downloaded; UpGuard said it had been asked not to reveal which agency made the request.