The 20-year-old Australian university student who found secret US military bases with fitness tracker technology is worried how others may do the same.
Nathan Ruser made international headlines on Monday when he showed heat maps from fitness tracking company Strava Labs could potentially unmask secret US military bases.
Mr Ruser - who is studying international security at Australian National University - tweeted his discovery to the world.
The student told US network ABC on Tuesday he was exploring a map when he wanted to see if it would show US troops inside Syria.
"It was very clear to see what you knew were US bases lighting up so much clearer than any of the rest of the country," he said.
But Mr Ruser said he had several "big concerns" with the data.
"Firstly, it allows an unprecedented look at the geographic build of a lot of these bases," he said.
Heat maps from fitness tracking company Strava Labs could potentially unmask secret US military bases. Source: AFP
"You can see the supply lines, you can see the patrol routes in some cases, and you can see the infrastructure within the bases.
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"But more than that, one of the most important and disturbing elements of the map is that it's possible to establish an understanding of how (a) base works."
"It shows you which buildings the military personnel prefer. It can show you how military personnel like to get from one part of the base to another and even where they take their afternoon jogs.
"(This) is something very valuable if you are looking to target the base."
Mr Ruser told ABC News in Australia that the bases he found were "vaguely known about but not often talked about."
"You could see immediately that those are what shone and those are what lit up, and zooming in you could just see an incredible amount of geographic and dynamic detail about how those bases are used," he said.
The Pentagon said on Monday said it will review how US troops use fitness trackers and other devices.