Members of the U.S. military are being instructed to hide their identities on social media websites by replacing their profile images with cartoons or avatars.

A series of guidance documents have been circulated by the FBI among military units warning personnel and their families to conceal their faces when using sites including Facebook, Twitter, LinkedIn, and Google+. The warnings have apparently been prompted by concerns that Islamic State militants could use social media to identify targets in the United States.

The documents contain advice on how to ensure privacy online, and feature a series of social network “dos and don’ts.” They urge that military employees:

Avoid posting or tagging images of you or your family that clearly show your face. Select pictures taken at a distance, at an angle, or otherwise concealed. Never post smartphone photos, and don’t use your face as a profile photo. Instead, use cartoons or avatars.

The FBI makes a variety of suggestions designed to limit how members of the military can be identified online. For example, the bureau suggests not using hashtags on Twitter so as “to avoid being indexed and associated with a topic by Twitter search.”

The guidance papers were circulated in recent weeks, according to military sources, prior to a new warning about potential Islamic State attacks issued by the FBI over the weekend. The bureau issued a bulletin Sunday telling military staff that “overseas based individuals are looking for like-minded individuals in the U.S. to carry out these attacks,” adding: “we also request members of the military review their online social media presence for any information that might attract the attention of violent extremists.”

In September, Homeland Security officials told Congress that there was no current intelligence suggesting Islamic State militants were plotting attacks on the United States. The group’s “ability to carry out complex large-scale attacks in the West is currently limited,” said Nicholas Rasmussen, deputy director of the National Counterterrorism Center. The greater concern among security officials is likely the possibility of lone-wolf-style attacks against military personnel, of the kind seen more recently in Canada and the United Kingdom.

The Department of Defense had not responded to a request for comment on this post at time of publication.

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