Named Adam Sitzes, the United States Air Force intelligence officer, reportedly used the tasking website Trello to upload a series of documents classified under secret information acts.
With the platform being in the public domain, and not hidden behind sophisticated state firewalls and protection, the information could have easily been obtained by hostile nations.
Information uploaded onto the card-based tasking site included details of the RAF’s Typhoon fighter jets, as well as a list of names of US counter-terrorism officers based in the United Kingdom, according to reports.
The haphazard spy is then said to have forgotten the files were public, leaving them “gift-wrapped” for Chinese and Russian agents to find.
Further to the information about RAF assets, Mr Sitzes also allegedly exposed various US arms deals, as well as emails listing the names of National Security Agency staff in the US, equivalent to Britain’s own GCHQ.
Furthermore, the list of names found on the cards included top officials from the US, UK and NATO.
Upon discovering the news, a source said: “These types of errors end careers.”
According to reports, thousands of documents were uploaded onto the Trello website.
The app allows users to access the files from any device with relatively simple login details, hence allowing users to work from anywhere when using the software.
The Sun was alerted to the leak when discovered and was able to find the information and data in seconds using a simple Google search.
Upon realising the severity of the problem, the tabloid contacted Whitehall who used emergency means to contact the US to remove all the files.
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In recent times, there have been several high profile leaks and gaffs by intelligence officers and former staff.
The most notable is US spy Edward Snowden who leaked highly classified information from the NSA in 2013.
With hundreds of thousands of top-secret files exposed, the computer intelligence consultant fled to Moscow where he was granted asylum.
Also from the US was Bradley Manning, now Chelsea, who was an activist and whistle-blower.
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Mr Manning, a former US soldier leaked around 750,000 documents to Wikileak exposing details of the war in Iraq amongst other information.
Jailed and transitioned into a woman, Ms Manning had her sentence commuted in 2017 after serving seven years behind bars.
This year, Danish spy chief Lars Findsen, the head of the country’s foreign intelligence unit, equivalent to MI6, was arrested and charged with leaking documents to hostile states.
Mr Findsen denied the charges and told reporters at the hearing: “I want the charges brought forward and I plead not guilty.
“This is completely insane.”
The exact charges and nature of the alleged leaks have not been made public.
But the case against Mr Findsen, who had led Denmark’s foreign intelligence agency since 2015, and its domestic counterpart before that between 2002 and 2007, has been described as unprecedented.
Danish prosecutors have not commented on the case, nor have lawyers for Mr Findsen.