War

War is direct combat between two or more sides, each attempting to impose its will on the other, typically using weapons or military force. The term is used to describe engagements involving regular armed forces, armed non-state groups, and even conflicts between individuals.

War is a component of the broader phenomenon of warfare, though the two are not identical. War refers to a specific combat action occurring at a defined time and place, whereas warfare is a political and military condition that persists over a prolonged period. War can also be part of peacekeeping or police military operations that are not designated as war.

Levels of war

Military analysts divide war into levels: the strategic level (overall decisions and war aims), the operational level (the method of troop movement), and the tactical level (what occurs when the two sides meet). Also relevant is the 'battlefield' — the location where combat takes place. Engagement between the two sides depends on weapons, terrain, intelligence, and communication.

Types

War is classified by the domain in which it occurs: land war, naval war, air war, and today electronic and cyber war. There is also a distinction based on method: conventional war, in which forces are clearly defined and confrontational, and unconventional war such as insurgency and asymmetric war, in which a weaker side employs rapid strikes and attrition.

International law

International humanitarian law — codified in the Geneva Conventions and the customary laws of war — regulates the conduct of war. Key principles include the distinction between combatants and civilians, proportionality of expected damage, and prohibition of certain weapons such as chemical agents. Prisoners of war receive special protection. Serious violations can constitute war crimes subject to international courts.

Effects

War causes death and injury, destruction of infrastructure, and mass displacement of populations. It also has psychological effects on participants and affected communities, which modern psychology recognizes as post-traumatic stress disorder (PTSD). Economically, war diverts state resources toward the military.