Original Contributions to Network Interdiction Theory with Applications to Critical Infrastructure Protection in Nigeria

Critical infrastructure networks in Nigeria, encompassing power transmission lines, petroleum pipelines, and transportation corridors, are vulnerable to deliberate interdiction by criminal and insurgent actors whose strategic targeting behaviour cannot be adequately modelled by conventional reliability analysis methods that assume random failure. This dissertation develops original contributions to network interdiction theory motivated by the critical infrastructure protection problem in Nigeria. A comprehensive review of network interdiction literature identifies fundamental gaps in multi-attacker interdiction models, dynamic interdiction games under incomplete information, and interdiction models accounting for defender capacity constraints and repair operations. The dissertation makes four original theoretical contributions: a multi-attacker network interdiction model with adversarial coalition formation; a dynamic interdiction game in which the attacker and defender alternate moves over a finite horizon with incomplete information about each other's resources; a budget-constrained optimal interdiction detection model for the defender; and structural results on the computational complexity of these model classes. Proof techniques from combinatorial optimization, game theory, and information economics are combined in novel ways. The theoretical models are applied to a case study of the Trans-Forcados Pipeline network in the Niger Delta, using an original interdiction event dataset compiled from industry and security reports. Results identify the minimum-cost defender hardening strategy that increases the minimum attacker budget required for successful network interdiction by 67 percent. The dissertation advances network interdiction theory while contributing directly relevant insights for critical infrastructure security policy in Nigeria. Keywords: network interdiction, critical infrastructure, game theory, pipeline security, Niger Delta