Federal law enforcement terror bulletins have become as much a part of the holiday season in the past decade as egg nog and department store Santas.
But this year, which ends amid a heightened concern over terror, is a little different. A Department of Homeland Security bulletin sent to law enforcement nationwide Thursday says that federal authorities worry terrorists will try to rattle Americans by attacking during the holidays, and lists concerns including car bombs, trucks ramming crowds and a Mumbai-style small arms attack.
"We are concerned these terrorists may seek to exploit the likely significant psychological impact of an attack targeting mass gatherings in large metropolitan areas during the 2010 holiday season, which has symbolic importance to many in the United States," The "Security Awareness for the Holiday Season" bulletin states.
The bulletin cites no specific threats for Christmas and New Year's, but makes clear that this year's enhanced concern is based on a persistent, evolving threat. The past 12 months brought multiple attempted attacks on U.S. targets, including the attempted Christmas Day underwear bombing of Northwest 253, Faisal Shahzad's failed Times Square car bomb, the "printer bomb" cargo plane plot and a number of alleged would-be bombers caught in stings in Oregon and elsewhere.
"During the last year," said the bulletin, "al-Qa'ida in the Arabian Peninsula (AQAP) and Tehrik-e Taliban Pakistan (TTP) have attempted to carry out attacks in the United States, thereby raising their international profile. We cannot discount the possibility that other al-Qa'ida-linked groups, such as al-Qa'ida in Iraq, al-Qa'ida in the Islamic Maghreb, Lashkar-e Tayyiba, or al-Shabaab, will attempt to target the Homeland during the holiday season."
The document suggests that terrorists may consider public gatherings like "sporting events, parades, religious and cultural activities" to be attractive targets. "Attacks against these targets could maximize the psychological impact on the American public given the symbolic importance of the holiday season to many in the United States," says the bulletin. "Attacks against air cargo during this busy season are also a concern."
"While terrorists will strike when and where they can, holiday periods do pose a particular window of vulnerability and are appealing targets of opportunity for terrorist attacks," said Frank Cilluffo, director of the Homeland Security Policy Institute at George Washington University. "This is underscored in the recent failed attempts in Oregon and Sweden and [accused underwear bomber] Abdulmutallab's attempt last Christmas."
The most recent attempt came in Sweden on Saturday, where a terrorist who was apparently planning a large attack in central Stockholm blew up a suicide belt, killing himself and wounding two bystanders, after one of the explosive devices he had prepared detonated prematurely in his car, setting the car on fire.
Don Borelli, former assistant special agent charge in of the FBI Joint Terrorism Task Force in New York, said that despite the absence of a specific threat, this year stands out.
"There are a couple of key concerns here that make it a little more unusual than the norm including the printer bomb plot," said Borelli.