FBI, NCTC warn terrorists may target US military bases on national holidays

American investigators, who are having hard time trying to keep up with the social media barrage by U.S.-based supporters of Islamic State (IS), have reportedly warned that "U.S. military bases, locations, and events" could be targeted in the near-term.

A six-page bulletin cited by Fox News urged law enforcement and specifically military personnel to be vigilant during upcoming national holidays and military events due to the "heightened" threat of attacks by the IS.

The bulletin, released jointly by the Federal Bureau of Investigation, Department of Homeland Security and National Counterterrorism Center, although said that there was no "credible" information targeting events on U.S. federal holidays but pointed to "heightened chatter" and urged people to take precautions.

The list of "observable behaviors" also pointed to so-called insider threats, and warned about individuals asking "unusual questions" about building maintenance or security procedures.