The Pentagon's internal security agency, the Pentagon Force Protection Agency, sent out an internal memo to its personnel last week that they could potentially be targets for ISIL or other terrorist groups, and to take appropriate precautions.
The memo states that no specific threats have been received, but ISIL and other terrorist group members do "view U.S. military members and law enforcement officers as legitimate targets for attacks", and that "targets in recent ISIL-linked terrorist plots included places of public gatherings, government entities, mass transit nodes, and religious facilities. Attacks would most likely involve edged weapons, small arms, or improvised explosive devices, and could be perpetrated with little-or-no advanced warning. In light of these threats and recent attacks in the United Kingdom, France, and Canada, remaining vigilant is paramount.”
Many precautions that the memo mentions taking are standard practices for Pentagon employees on social media, such as: avoid posting anything on social media opposing ISIL or other terrorist groups, check privacy settings and change passwords regularly for social media accounts, and to be careful about posting anything online identifying them with law enforcement or the military.
Additional precautions include concealing DoD, law enforcement, or military badges, decals, or other forms of ID, vary your route to and from work, and be aware and on guard when in public and/or large crowds.
The full text of the memo is available on MilitaryTimes.com here (PDF).