Proportionality, Territorial Occupation, and Enabled Terrorism

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Some collateral harms affecting enemy civilians during a war are agentially mediated – for example, the US-led invasion of Iraq in 2003 sparked an insurgency which killed thousands of Iraqi civilians. I call these ‘collaterally enabled harms.’ Intuitively, we ought to discount the weight that these harms receive in the ‘costs’ column of our ad bellum proportionality calculation. But I argue that an occupying military force with de facto political authority has a special obligation to provide minimal protection to the civilian population. As a result, when an occupying military force collaterally enables a harm affecting the civilian population, the weight that the harm ought to receive in the ad bellum proportionality calculation is unaffected by the fact that the harm is agentially mediated – it ought to be weighed at least as heavily as those harms that the occupying force collaterally commits directly. As a result, satisfying the ad bellum proportionality constraint in wars of territorial occupation is more difficult than it has been thought.