For local police departments searching for ways to stop terrorist acts before they occur, this does not bring much comfort. When looking at these attacks, officers might get the impression that there is not much they can do about terrorism other than improving physical security at high-risk targets.
But were these infamous terrorists typical?
Although we know a great deal about the behavior of traditional criminals, little information has been available about terrorists. Are they much different from conventional criminals, who tend to commit their crimes close to home?[1] Research has shown that traditional criminals are spontaneous, but terrorists seem to go to great lengths preparing for their attacks — and may commit other crimes while doing so. How long does this planning take? And do different types of terrorist groups vary in preparation time?
To help answer these questions, the National Institute of Justice (NIJ) launched a series of projects to explore patterns of terrorist behavior.[2] In the first of these projects, a panel of experts[3] was assembled to examine 60 case studies involving terrorist incidents in the U.S. during the past 25 years.[4] These cases involved the four major types of U.S. terrorist groups: left wing, right wing, single issue and international.[5],[6],[7] The panel — including this author — looked at the homes of the terrorists, the locations of planning and preparation, and the sites of the terrorist incidents to discover whether any patterns emerged.
What we learned was intriguing: The cases of McVeigh, the Sept. 11 hijackers and Rudolph are actually unusual. In fact, we found that most terrorists live close to their selected targets, and they engage in a great deal of preparation — some over the course of months or even years — that has the potential of coming to the attention of local law enforcement.
Terrorists Think Globally but Act Locally
We studied:
- Ten attacks by international groups that involved 93 preparatory acts.
- Fourteen attacks by right-wing groups that involved 55 preparatory acts.
- Twenty-nine attacks by environmental groups that involved 80 preparatory acts.
- Six attacks by left-wing groups that involved eight preparatory acts.
According to our analysis, almost half (44 percent) of all terrorists examined lived within 30 miles of their targets. (See Exhibit 1. Distance From Terrorist Residence to Target (All Groups).) When the types of terrorist groups are examined separately, however, the findings are much different.
International terrorists lived relatively near their targets, whereas right-wing terrorists lived in rural areas but selected targets reflecting the "pollutants of urban life" in nearby cities.
Terrorists most commonly prepared for their attacks with surveillance and intelligence gathering, robberies and thefts to raise funding for the group, weapons violations, and bomb manufacturing. Again, most of these behaviors took place relatively near their homes, which, in turn, were close to the targets. Terrorists may stay close to home because of new immigration status, lack of transportation, lack of knowledge of the urban landscape or a desire to avoid attention. Among single-issue terrorists in particular, 71 percent of the preparatory acts occurred within 12 miles and 92 percent within 28 miles of the target. This finding may also be attributed to the use of "uncoordinated violence" tactics by these environmental and anti-abortion extremists, which often results in local targeting by "lone wolves" sympathetic to the cause.
A separate follow-up NIJ project[8] that analyzed the distance between more than 250 environmental and international terrorists' homes and their targets confirmed the earlier preliminary findings that their spatial patterns are fairly similar. The analysis found that about half of the environmental terrorists and nearly three-fifths of the international terrorists lived within 30 miles of their targets. (See Exhibit 2. Distance From Environmental Terrorist to Target and Exhibit 3. Distance From International Terrorist Residence to Target.) Sixty-five percent of the environmental terrorists and 59 percent of the international terrorists prepared for their attacks within 30 miles of their target sites.
Although the terrorists studied committed most of their preparatory offenses near their homes, they conducted robberies, burglaries and thefts much farther away — an average of 429 miles from home. This suggests that most environmental and international terrorists live near the selected target and conduct surveillance and other general preparation near their homes and the eventual location of the attack. Major crimes to procure funding for the group — like thefts, robberies and burglaries — however, are intentionally committed many miles away to avoid drawing attention to the group's location and target choice.
The Terrorist's Timepiece
We found that preparations generally began less than six months before the attack and ended with a flurry of actions a day or so before. This pattern varied by group type. Single-issue and right-wing terrorists engaged in substantially less preparatory crime over a shorter period — once again, most likely reflecting the use of "leaderless resistance" and lone-wolf strategies. The planning cycle of international terrorists tended to be longer. (See Cumulative Percentage of Preparatory Acts Over Time.)
In our follow-up study, we took a closer look at the specific patterns of international and environmental terrorists by placing the preparations for all incidents on a time line. For instance, we examined the 21 incidents attributed to the environmental terrorist group known as "The Family," which was responsible for the Vail, Colo., ski resort arson in 1998 and many attacks against Forest Service and Bureau of Land Management buildings from 1996 to 2000. The Family consisted of at least 16 people. Unlike most environmental terrorists who use uncoordinated violence and lone-wolf strategies, the group's actions were more spontaneous than other environmental cases, with a short preparation period and little extended planning. Eighty-five percent of their known preparation activities — typically, inspection of the target, purchase of bomb-making items from local stores and identification of a staging area a short distance from the target — occurred within six days of the planned attack. An explosive device was assembled at the staging area a day or so before the incident and then delivered to the target. Participants usually returned to the staging area to destroy any evidence.
International terrorists, on the other hand, engaged in nearly three times as many preparatory acts per incident as their environmental counterparts. This may be due to the larger number of people usually involved in international incidents, the size and scope of the planned incident or simply a longer planning cycle. Comparing the 10 international terrorist incidents that occurred on American soil,[9] we found that the average planning cycle for international terrorists was 92 days, as opposed to 14 days for environmental terrorists. Averages can be misleading, however, because of significant outliers, such as the multiyear planning cycle of the Islamic extremists seeking to destroy New York City landmarks in the mid-1990s. Whereas environmental terrorists committed an overwhelming majority of their preparatory activities in the week before the incident, international terrorists took up to six months to prepare.
Arming Police With Knowledge
For law enforcement agencies, the implications of these patterns are significant. Committing an act of terrorism will usually involve local preparations. Although much of this conduct will not necessarily be criminal, early intelligence may give law enforcement the opportunity to stop the terrorists before an incident occurs. Knowledge of the threat — for example, understanding how long environmental or international terrorists prepare for their attacks — will affect the manner in which local officials respond. Identifying preparatory actions by environmental extremists may signal that an attack is imminent, whereas similar behavior by an international group might suggest that an attack is still several months away.
Understanding that most terrorists "act locally" can be important to know as investigative agencies seek to prevent terrorism and arrest those commit such acts. These local patterns may be used by agencies to more efficiently patrol known, high-risk target areas and gather intelligence on suspected actions within a specific distance from potential targets. As we continue to deepen our understanding of the relationship among the location of the terrorist's home, terrorist preparation activities and the target, this growing knowledge should help officers prevent and respond to attacks.
Cumulative Percentage of Preparatory Acts Over Time
| Type of Terrorist Group | Incident Day | Day before | 2-3 days | 4-7 days | 8-14 days | 15-30 days | 1-3 mos | 4-6 mos | 7-12 mos | 1-3 yrs | 3+ yrs |
|---|---|---|---|---|---|---|---|---|---|---|---|
| International | 5% | 9% | 13% | 21% | 32% | 55% | 68% | 84% | 89% | 97% | 100% |
| Right wing | 15% | 26% | 31% | 44% | 49% | 67% | 94% | 96% | 96% | 100% | |
| Environmental | 20% | 43% | 72% | 80% | 91% | 95% | 98% | 100% | |||
| Left wing | 50% | 75% | 88% | 88% | 88% | 88% | 100% | ||||
| All categories | 13% | 27% | 40% | 48% | 57% | 72% | 85% | 93% | 95% | 99% | 100% |
For each case study, researchers analyzed when terrorist groups performed preparatory acts that led to the attacks. They learned that international terrorists typically began their preparations 3+ years before an attack; right-wing terrorists at one to three years; environmental terrorists at four to six months; and left-wing terrorists at one to three months. The cumulative percentages of the acts for each group are as follows:
International Terrorists. By the day of the incident, international terrorists had completed all but five percent of their preparatory acts; by the day before the incident, they had completed all but nine percent; by two to three days before, they had completed all but 13 percent; by four to seven days before, they had completed all but 21 percent; by eight to 14 days before, they had completed all but 32 percent; by 15 to 30 days before, they had completed all but 55 percent; within one to three months of the incident, they still had 68 percent of their preparatory acts to complete; within four to six months, they still had 84 percent to complete; at seven to 12 months, they had 89 percent to complete; between one and three years, they had 97 percent to complete; and at 3+ years, 100 percent of their preparatory acts were not yet completed.
Right-Wing Terrorists. By the day of the incident, right-wing terrorists had completed all but 15 percent of their preparatory acts; by the day before the incident, they had completed all but 26 percent; by two to three days before, they had completed all but 31 percent; by four to seven days before, they had completed all but 44 percent; by eight to 14 days before, they had completed all but 49 percent; at 15 to 30 days before the incident, they still had 67 percent of their preparatory acts to complete; within one to three months, they had 94 percent to complete; at four to six months and seven to 12 months, they had 96 percent to complete; and between one and three years, 100 percent of the preparatory acts were not yet completed.
Environmental Terrorists. By the day of the incident, environmental terrorists had completed all but 20 percent of their preparatory acts; by the day before the incident, they had completed all but 43 percent; at two to three days before, they still had 72 percent of their preparatory acts to complete; at four to seven days before, they still had 80 percent to complete; at eight to 14 days before, they had 91 percent to complete; at 15 to 30 days before, they had 95 percent to complete; within one to three months, they had 98 percent to complete; and within four to six months, 100 percent of their preparatory acts were not yet completed.
Left-Wing Terrorists. By the day of the incident, left-wing terrorists had completed all but 50 percent of their preparatory acts; on the day before the incident, they still had 75 percent of the acts to complete; at two to three days, four to seven days, eight to 14 days and 15 to 30 days before, they had 88 percent to complete; and within one to three months, 100 percent of their preparatory acts were not yet completed.
All Terrorists. By the day of the incident, all terrorists had completed all but 13 percent of their preparatory acts; by the day before the incident, they had completed all but 27 percent; by two to three days before, they had completed all but 40 percent; by four to seven days before, they had completed all but 48 percent; by eight to 14 days before, they had completed all but 57 percent; at 15 to 30 days before the incident, they still had 72 percent of their preparatory acts to complete; within one to three months, they still had 85 percent of their preparatory acts to complete; within four to six months, they had 93 percent to complete; at seven to 12 months, they had 95 percent to complete; between one and three years, they had 99 percent to complete; and at 3+ years, 100 percent of their preparatory acts were not yet completed.
About This Article
This article appeared in NIJ Journal Issue 260, July 2008.