Guerrilla characteristics are shared by private armies, mercenaries, terrorists, militants, revolutionaries, freedom fighters, irregulars, outlaw gangs, highwaymen and brigands. Hit-and-run tactics are their hallmark although, when in force, they are capable of pitched battles. Modern communications and weapons have transformed the lonely, independent bands of men, each armed with a rifle, into well-disciplined forces. They are armies that are mobile, frequently fighting a defensive war whose only objectives are harassment, destruction, and, if possible, attrition of the enemy. Given this, they strike at will with no overall military strategy that can be anticipated, unless they are on near-equal terms with their enemy, at which time they act more like regular military forces.
Guerrillas are legitimatized when reconstituted as government forces. This occurred in the former Soviet Union after World War I, and after the Cuban Revolution under Fidel Castro. Otherwise they are illegitimate and their fighters come under no international treaty for protection of combatant human rights. Likewise, guerrilla fighters may not observe Geneva Conventions or other so-called humane conventions of warfare. Viet Cong guerrilla terrorism directed against villagers is a conspicuous example.