WASHINGTON -- Deployed service members may have to ditch their fitness trackers in response to a new memo from Deputy Defense Secretary Patrick M. Shanahan prohibiting the use of GPS functions in deployed locations.

This includes physical fitness aids, applications in phones that track locations, and other devices and apps that pinpoint and track the location of individuals.

“Effective immediately, Defense Department personnel are prohibited from using geolocation features and functionality on government and nongovernment-issued devices, applications and services while in locations designated as operational areas,” Pentagon spokesman Army Col. Robert Manning III told Pentagon reporters today.

Deployed personnel are in “operational areas,” and commanders will make a determination on other areas where this policy may apply.

The market for these devices has exploded over the past few years, with many service members incorporating them into their workout routines. They use the devices and applications to track their pace, running routes, calories burned and more. These devices then store the information and upload it to central servers where it can be shared with third parties. That information can present enemies with information on military operations.

Using GPS Devices Pose Risk

“The rapidly evolving market of devices, applications and services with geolocation capabilities presents a significant risk to the Department of Defense personnel on and off duty, and to our military operations globally,” Manning said.

These Global Positioning System capabilities can expose personal information, locations, routines and numbers of DoD personnel. Their use in overseas locations “potentially create unintended security consequences and increased risk to the joint force and mission,” Manning said.

Personal phones and other portable devices also contain apps that rely on GPS technology, and they will be affected. Commanders will be responsible for implementing the policy, and they will be allowed to make exceptions only after conducting a thorough risk assessment.

Security is at the heart of this guidance. DoD seeking a balanced way that allows for legitimate official and personal uses of geolocation technology that does not impact security.

Manning said the department will continue to study the risk associated with these devices and change the policy as needed.