Thanks to recent advances in machine learning, facial-recognition technology can pick faces out of a crowd with impressive accuracy. But just how far away from their subjects can cutting-edge facial-recognition systems work? According to a new report, a whole lot further than you probably think. So far, in fact, that the person identified may not even realize that they were caught on camera in the first place.

New Scientist writes that the United States military is in the process of funding the creation of a portable face-recognition device that’s able to identify individuals from up to 1 kilometer away. That’s the equivalent of almost 11 football fields.

The project, titled Advanced Tactical Facial Recognition at a Distance Technology, began in 2016. A working prototype of the system was demonstrated at the end of last year. Research by the U.S. Special Operations Command (SOCOM) is reportedly ongoing, although there’s no word on when this technology will see the light of day.

The tech has been developed by Arlington, Virginia-based firm Secure Planet. On its website, the company states that its “mobile biometric verification and identification system provides critical protection to soldiers and civilians, allowing them to stay safe in ever-evolving high threat environments.” It adds that it is “committed to providing innovative products that will forge our way to a more secure planet.”

The firm doesn’t reveal exactly how its technology works. Even with cutting-edge A.I., it’s a massively challenging problem to solve, since adding longer lenses to cameras increases noise from the vibrations. At these kinds of distances, atmospheric turbulence can also pose a problem when it comes to distorting the image in an effect similar to the heat shimmer seen on hot days. To get around this, a separate neural network could potentially be used to unscramble the distorted image in order to get workable facial data for identification purposes.

It’s also not clear exactly how the technology will be deployed. While it was originally designed for handheld use, it could also reportedly be used with drones. SOCOM documents say that it could possibly be shared with law enforcement agencies.