Deployed Security Games for Patrol Planning

Abstract

Nations and organizations need to secure locations of economic, military, or political importance from groups or individuals that can cause harm. The fact that there are limited security resources prevents complete security coverage, which allows adversaries to observe and exploit patterns in patrolling or monitoring, and enables them to plan attacks that avoid existing patrols. The use of randomized security policies that are more difficult for adversaries to predict and exploit can counter their surveillance capabilities and improve security. In this chapter we describe the recent development of models to assist security forces in randomizing their patrols and their deployment in real applications. The systems deployed are based on fast algorithms for solving large instances of Bayesian Stackelberg games that capture the interaction between security forces and adversaries. Here we describe a generic mathematical formulation of these models, present some of the results that have allowed these systems to be deployed in practice, and outline remaining future challenges. We discuss the deployment of these systems in two real-world security applications: 1) The police at the Los Angeles International Airport uses these models to randomize the placement of checkpoints on roads entering the airport and the routes of canine unit patrols within the airport terminals.2) The Federal Air Marshal Service uses these models to randomize the schedules of air marshals on international flights.

Catastrophe and Rational Policy: Case of National Security

“…One example is police officers strolling in the streets of a neighborhood. Security examples include airport scanners, additional patrol boats, or improving firearms for security guards (Ordónez et al 2013). This is in keeping with the conclusions of the 9/11 report (Roth, Greenburg, and Wille 2004) in which the adversary observes government effort by observing the extent that targets are protected.…”

“…Other forms of informational imperfections can exist where secrecy is a key strategic asset to each party. For example, in the case of government effort, the U.S. Coast Guard randomizes its surveillance and counter‐insurgency efforts, suggesting mixed strategy games as the appropriate modeling framework (Ordónez et al 2013). We do not focus on mixed strategy or asymmetric information games as their relevance is tactical , such as in the Coast Guard example, whereas our focus is on the broader policy issues measured by the budgetary priorities of the U.S. government that are measurable and readily observed.…”

Terrorism risk and optimal policy response: theory and empirics

“…On one hand, secrecy may be a key strategic asset of a defending government, suggesting that, not only the adversary, but also even the defending government may withhold key defensive information. For example, in the case of government effort, the US Coast guard randomizes its surveillance and counter-insurgency efforts (Ordónez et al , 2013), in a mixed strategy incomplete information game to keep the opponent uncertain. On the other hand, by showing and revealing its robust defensive expenditures and effort level, a defending government may be able to deter potential adversary plots.…”

“…We justify this by noting that many of the strategic decisions of the government are visible to the adversary and common knowledge. Examples include airport scanners, additional patrol boats, or improving firearms for security guards (Ordónez et al , 2013). Government efforts reduce the probability of a successful attack ( P s ) in equation (2), both directly through the effect of g on P s , and indirectly through the effect of g on adversary optimal effort ( a *) in equation (5), and in turn a * on P s .…”