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."
Holidays Are 'Appealing Targets of Opportunity For Terrorist Attacks'
"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.
The DHS memo cites a range of possible attack options by terrorists. "Based on our review of historical Homeland and overseas terrorist plots, we assess that terrorists plotting an attack within the United States could use IEDs placed and abandoned at predetermined locations or carried or worn by suicide operatives, remotely detonated multiple IEDs that are timed for sequential explosions, or VBIEDs [car bombs].Terrorists could also use tactics featuring small arms to conduct an attack, possibly in combination with IEDs."
New York City police conducted a drill to prepare for a Mumbai-style small arms attack earlier this year.
'Terrorist Use of Vehicle Ramming Tactics'
Worries about vehicle-borne threats were brought up in three earlier DHS briefing memos sent to law enforcement that are circulating with the holidays approaching. The bulletins warn of possible attacks from tractor trailers and buses, the use of vehicles to breach security perimeters, and "Terrorist Use of Vehicle Ramming Tactics."
"The ramming warning likely comes from an online Al Qaeda magazine, which advocated attaching blades to a pickup and driving into a crowd in Washington, D.C.," said Borelli, now a senior v.p. of the Soufan Group, a security consulting firm. The tactic was recommended in a summer issue of Inspire, Al Qaeda in the Arabian Peninsula's webzine.
The most recent bulletin to mention vehicle ramming, a "Roll Call Release" dated this Monday, says the tactic "offers terrorists with limited access to explosives or weapons an opportunity to conduct a Homeland attack with minimal prior training or experience."
An earlier Roll Call Release dated June 10 and now recirculated, states, "Terrorists could use large commercial motor vehicles ... such as trucks or buses loaded with explosives or toxic industrial chemicals as weapons to attack public gatherings; secure or sensitive sites such as airports, power facilities, critical bridges and tunnels, or fuel depots. A terrorist also could use a CMV as a battering weapon."
And a third release also dated June 10 states, "Analysis of attacks by violent extremist groups overseas reveals that attackers seek ways to circumvent or overcome fencing, access road barriers, and similar perimeter security measures to gain access to their primary target. Law enforcement and security personnel should be aware that individuals seeking to conduct an attack in the United States may attempt unorthodox or unexpected measures, such as using improvised ramps, to bypass obstacles."
Combined, the circulars demonstrate the level of concern about what top officials have already acknowledged is a significant uptick in the terrorists' operational tempo.
Said Cilluffo, "The jihadi threat we face today has metastasized and comes in various shapes, sizes, flavors and forms, ranging from Al Qaeda senior leadership to its affiliates in [Pakistan's] Tribal Areas and Waziristan, Yemen , Somalia, the Maghreb and increasingly the Caucasus, to homegrown jihadists. "
The DHS holiday bulletin also reminds readers, however, that "the timing of a terrorist attack depends more on terrorists' readiness to execute" it than on the calendar.