U.S. military troops and other defense personnel at sensitive bases or certain high-risk war zone areas won't be allowed to use features on fitness trackers or cellphone applications that can reveal their location, according to a new Pentagon order.

The memo stops short of banning the devices, which are often linked to cellphone apps or smart watches and can share users' GPS locations and exercise details to social media. But it says the "geolocation capabilities" can present a "significant risk" to military personnel, so those functions must be turned off in certain operational areas.

Under the new order, military leaders will be able to determine whether troops under their command can use the GPS function on their devices, based on the security threat in that area or on that base.

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"The rapidly evolving market of devices, applications, and services with geolocation capabilities (e.g., fitness trackers, smartphones, tablets, smartwatches, and related software applications) presents significant risk to Department of Defense (DoD) personnel both on and off duty, and to our military operations globally," the order says.

It adds, "These geolocation capabilities can expose personal information, locations, routines, and numbers of DoD personnel, and potentially create unintended security consequences and increased risk to the joint force and mission."

Defense personnel who aren't in sensitive areas will be able to use GPS applications if their commanders conclude it doesn't pose a risk. For example, troops exercising at major military bases around the country, such at Fort Hood in Texas or Norfolk Naval Station in Virginia, would likely be able to use the location software on their phones or fitness devices. Troops on missions in more sensitive locations, such as Syria, Iraq, Afghanistan or parts of Africa, meanwhile, would be restricted from using the devices or be required to turn off any location function.

Concerns about exercise trackers and other electronic devices made headlines in January in the wake of revelations that an interactive, online map was pinpointing troop locations, bases and other sensitive areas around the world. The Global Heat Map, published by the Strava fitness app, used satellite information to map the locations of subscribers to Strava's fitness tracking service.

At the time, the map showed activity from 2015 through September 2017. And while heavily populated areas were well lit, war zones such as Iraq and Syria showed scattered pockets of activity that could denote military or government personnel using fitness trackers as they move around.

The Pentagon immediately launched a review, noting that the electronic signals could potentially disclose the location of troops who are in secret or classified locations or on small forward operating bases in hostile areas.

This is the second memo affecting the use of electronic devices that the department has released in recent months. In May, defense officials laid out new restrictions for the use of cellphones and other mobile wireless devices inside the Pentagon.

That memo called for stricter adherence to long-held practices that require phones be left in storage containers outside secure areas where sensitive matters are discussed. But it also stopped short of banning the devices, and instead made clear that cellphones can still be used in common areas and other offices in the Pentagon if classified information is not present.

The latest memo says the new restrictions include GPS functions on fitness trackers, phones, tablets, smart watches and other applications.

The Pentagon also said it will provide additional cybersecurity training to include the risks posed by the trackers and other mobile devices.