Location tagging poses plenty of problems for civilians. Let’s say you told your boss that you were sick, but instead had plans to catch a Yankees game. In that case, you probably don’t want your next post popping up on Facebook “from Yankee Stadium.” While unwanted geotagging through services like Facebook, Twitter, Foursquare, and more is definitely an annoyance to many of us, it could be a matter of life or death to someone in the military.

That’s why the U.S. Army is warning soldiers about the dangers of geotagging.

The threat is pretty obvious. Not only could voluntarily sharing a location compromise a mission, but so much that’s done on a smartphone or tablet these days is geotagged, soliders could be sharing their locations without even knowing it.

“A deployed service member’s situational awareness includes the world of social media. If a Soldier uploads a photo taken on his or her smartphone to Facebook, they could broadcast the exact location of their unit,” said Steve Warren, deputy G2 for the Maneuver Center of Excellence.

“Today, in pretty much every single smartphone, there is built-in GPS,” Warren said. “For every picture you take with that phone, it will automatically embed the latitude and longitude within the photograph.”

In a post, the official site of the U.S. Army says that this has already happened. Back in 2007, as a new fleet of helicopters arrived at a base in Iraq, solider snapped some photos and out them online. Apparently, from those photos, enemies were able to single out the location and deliver a mortar strike that took out four AH-64 Apaches.

The Army is particularly concerned with Facebook – especially the new Timeline, which we all know, brings up all of your past Facebook information for the world to see. Users have to go back and manage their Timelines to make them ready for primetime.

“Some of those individuals have hundreds of ‘friends’ they may never have actually met in person, he explained. “By looking at someone’s map tab on Facebook, you can see everywhere they’ve tagged a location. You can see the restaurants they frequent, the gym they go to everyday, even the street they live on if they’re tagging photos of their home. Honestly, it’s pretty scary how much an acquaintance that becomes a Facebook ‘friend’ can find out about your routines and habits if you’re always tagging location to your posts,” said Staff Sgt. Dale Sweetname of the Online and Social Media Division.

The U.S. Army has some pretty in-depth social media guidelines, and they address what soldiers should do in terms of the geotagging issue. First off, they say that soldiers should never tag photos posted to Flickr or Picasa with locations, and they should refrain from using location-based social networking when deployed or during training. When engaged in operations, soldiers should just turn off the GPS function on their phones.