Counterinsurgency, recently known by the acronym COIN, is defined by Joint Publication 3-24 as “comprehensive civilian and military efforts designed to simultaneously defeat and contain insurgency and address its root causes.” It represents the state’s efforts to counter a violent challenge to its governing legitimacy by insurgents (for the insurgent side, see the entry “Guerrilla War”). Insurgent tactics, as articulated by Vladimir Ilyich Lenin and Mao Tse-tung, generally employ a blend of guerrilla tactics, coercion (terror and violence), propaganda (political education), a united front, legal political means, and “shadow governance” to supplant the existing authority.

To oppose these efforts, COIN theorists posit unique blends of force and public engagement, with the particular approach dependent on local conditions, available resources, and public support. The force side is ...