PurposeThe proliferation of terrorism worldwide raises the risk that terrorist strategies could evolve from conventional methods (e.g. suicide attacks) to biological, chemical and even radioactive and nuclear attacks (commonly abbreviated as CBRN) which are potentially much more dangerous. The authors make three contributions toward a better understanding of this risk and how it responds to counterterrorism measures.Design/methodology/approachThe authors develop a game that captures the terrorists’ potential strategic substitution between conventional and CBRN-type attacks; the authors calibrate the parameters of the game to real data using a novel calibration method and a partially unique dataset; they estimate the heavy-tailed distribution of attack severity and thus the probability of a successful attack, the underlying effort to launch an attack and the intrinsic difficulty of launching different types of attacks.FindingsThe authors find that in equilibrium, CBRN attacks, though less likely and more difficult to execute, are more deadly. In the end, the trade-off between, on one hand, the greater difficulty of carrying out a CBRN attack, and on the other, the greater deadliness of such an attack, points to a level of optimal counterterrorism spending by governments that weighs toward defending against CBRN attacks. The authors discuss these results and compare them with the actual level of counterterrorism spending by the US Government.Originality/valueThe framework of the game allows for substitution between the conventional and CBRN weapon types. These aspects of this paper, together with the unique calibration methodology, and the use of some unique terrorism data for the first time, are what distinguish this work from similar game theoretic papers in this area.

中文翻译：

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恐怖主义风险和最优政策反应：理论和经验

目的世界范围内恐怖主义的扩散增加了恐怖主义战略可能从传统方法（例如自杀式袭击）演变为生物、化学甚至放射性和核攻击（通常缩写为 CBRN）的风险，这可能更加危险。作者为更好地理解这种风险及其对反恐措施的反应做出了三项贡献。作者使用一种新颖的校准方法和部分唯一的数据集将游戏的参数校准为真实数据；他们估计攻击严重性的重尾分布，从而估计攻击成功的概率，发起攻击的潜在努力和发起不同类型攻击的内在难度。研究结果作者发现，在均衡状态下，CBRN 攻击虽然不太可能且更难以执行，但更致命。最后，一方面，实施 CBRN 攻击的难度越大，另一方面，这种攻击的致命性越大，这之间的权衡表明政府的最佳反恐支出水平对防御 CBRN 攻击。作者讨论了这些结果，并将它们与美国政府的实际反恐支出水平进行了比较。原创性/价值游戏的框架允许在常规武器类型和 CBRN 武器类型之间进行替代。本文的这些方面，连同独特的校准方法，