The NSA warned staff that smartphone apps can track them. Here are their recommendations to avoid tracking.

• The NSA warned members of the US military and intelligence community this week that their smartphone apps could be tracking them and put their security at risk.
• In guidance issued Tuesday, the agency noted that many apps make use of WiFi, GPS, and Bluetooth to collect cellphone location information, which is typically sold to advertisers or third parties.
• The agency recommended specific steps for staff to reduce their data exposure, like restricting app permissions and reducing web browsing on their smartphones.

The National Security Administration warned staff that the amount of data their smartphones track could pose a national security risk in new guidance issued Tuesday.

The guidance highlights a practice that's common across Silicon Valley products but rarely understood by consumers: smartphones are constantly gathering information on users' location, through a combination of apps, the smartphone's own hardware, and the telecommunications networks that they use.

Apps typically share that data with third-party brokers, who in turn sell it to clients including private companies and government agencies. The data is anonymized, meaning it's not directly tied to a person's identity — but researchers have consistently found that anonymized location data can easily be traced back to specific people.

"Location data can be extremely valuable and must be protected," the NSA guidance reads. "It can reveal details about the number of users in a location, user and supply movements, daily routines (user and organizational), and can expose otherwise unknown associations between users and locations."

Here are the steps the NSA recommends to minimize the amount of location data collected by your smartphone.

1. Disable location services in your device settings

Androids and iPhones will allow you to disable location services for specific apps or across the board. If you aren't actively using apps that require your location, disabling this will stop most apps from gleaning GPS data.

2. Minimize the permissions granted to your apps

That includes disabling apps' access to Bluetooth and location data in your device settings except when necessary, and steer clear of apps that require location.

"Avoid using apps related to location if possible, since these apps inherently expose user location data," the document reads.

3. Regularly reset your device's advertising ID.

Since advertisers are the entities most likely to track your location, resetting your advertising ID would make it harder to obtain a full picture of your movements.

Here are instructions on how to change your advertising ID on iPhone and Android.

4. Minimize web browsing and cloud storage

The NSA recommends that people who don't want their location to be found out should avoid web browsing on their mobile device, because cookies and tracking pixels used by websites can generate another form of location data. The document also recommends that people set their browser settings to disallow sharing location.

Read the full NSA guidance here.