"NORTHCOM has initiated FPCON BRAVO for all DoD forces. All personnel should remain vigilant for any suspicious activity. Report any concerns to the Law Enforcement Desk at 781-377-2315. This message is current as of 10:40 a.m. on May 1, 2011."
http://www.hanscom.af.mil/
Force Protection Conditions
FPCON BRAVO: Applies when an increased or more predictable threat of terrorist activity exists. Sustaining FPCON Bravo measures for a prolonged period may affect operational capability and military-civil relationships with local authorities.
http://www.nellis.af.mil/news/story.asp?id=123169728