For John, BLUF: Be careful out there.
On 24 October of this year the Defense Force Protection Agency issued a SECURITY ADVISORY, NO. 14-01, titled "Recent Threats and Individual Protective Measures".
Recent threats, revealed through various intelligence and law enforcement sources, indicate that terrorists, directed or inspired by the Islamic States of Iraq and the Levant (ISIL), view U.S. military members and law enforcement officers as legitimate targets for attacks. 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 (IEDs), 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.Note: ISIL, not ISIS.
Another Note: This is not really a big deal. I spend a year in the UK, on an RAF Station, when the Provisional IRA was blowing up RAF targets. And, it was an "open" base, in that a public right of way went through one corner of the base. We were not allowed to park in certain areas. We couldn't leave briefcases (back packs today) anywhere. We had a base pass for the windshield, but it was removed when we left the base. Simple precautions.
Final Note: You can help the police sort through the possible threats by not making yourself a problem. Like at the airport, don't leave your packages and wander off. Don't park where you are not supposed to. Follow directions from police or others. Stay calm, but think about a plan when in malls or other places with lots of people. Staying calm may be your best protection in the event of some untoward event. Remaining up tight all the time, when the odds of you being at the target at the time are very small, just means the other side is winning.
Regards — Cliff