Terrorists from a wide array of ideological influences and organizational structures consider security and risk on a continuous and rational basis. The rationality of terrorism has been long noted of course but studies tended to focus on organizational reasoning behind the strategic turn toward violence. A more recent shift within the literature has examined rational behaviors that underpin the actual tactical commission of a terrorist offense. This article is interested in answering the following questions: What does the cost-benefit decision look like on a single operation? What does the planning process look like? How do terrorists choose between discrete targets? What emotions are felt during the planning and operational phases? What environmental cues are utilized in the decision-making process? Fortunately, much insight is available from the wider criminological literature where studies often provide offender-oriented accounts of the crime commission process. We hypothesize similar factors take place in terrorist decision making and search for evidence within a body of terrorist autobiographies.

Environmental criminology is concerned with understanding the role of settings and geography more broadly in crime, as well as other related, proximal determinants of criminal activity with an emphasis on the role of person-situation interactions. 1 The approach has been very influential in shaping thinking and practice in crime prevention over the last forty years, growing hand in hand with the evidence-based policing movement. Insights from environmental criminology are increasingly prevalent within the study of terrorist behaviour. Much of the attention has been on the degree to which terrorist attacks are spatially and/or temporally clustered. 2 Other studies have focused upon the geographic and

This is the first study to apply a discrete choice model to understand terrorist spatial decision making. The findings support the proposition that terrorists make decisions that are guided by rationality and act in a similar way to urban criminals. A conditional logistic regression ascertained which characteristics increased the likelihood that an area would be selected as a target, using a dataset of attacks carried out by the Provisional Irish Republican Army in Belfast over a twentyyear period. An increase in distance from the terrorist's home to the attack site decreased the likelihood that an area would be chosen and an area was more likely to be chosen if it contained a major road, police station or military base.

Objectives To identify risk factors for bombings and bomb hoaxes committed by dissident Republicans in Belfast, Northern Ireland. Methods Risk terrain modelling (RTM) was applied to each type of incident to identify significant risk layers. Results Previous protests and riots [relative risk value (RRV) of 14.07; spatial influence (SI) of 100 m], punishment attacks (RRV 6.56; SI 300 m) and areas dense with pubs and bars (RRV 4.98; SI 200 m) were identified as risk factors for bombings. Punishment attacks (RRV 10.77; SI 100 m), police stations (RRV 8.76; SI of 200 m) and places dense with shops (RRV 6.94; SI 400 m) were identified as risk factors for bomb hoaxes. Descriptive statistics regarding predictive accuracy concluded that half of incidents for both types occurred in high or very high risk cells in a 3-year post-study period. Conclusions RTM could be a useful tool in guiding targeted responses to the dissident Republican threat in Belfast. The results suggest that there is some assessment of risk by the offenders, and that they are selecting targets rationally. Due to the differences in risk factors for the two types of events it can be proposed that there may be differences between targets relevant to ideology and realistic targets with increased chance of success.

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