Guerrilla tactics are based on intelligence, ambush, deception, sabotage, and espionage, undermining an authority through long, low-intensity confrontation. It can be quite successful against an unpopular foreign or local regime, as demonstrated by the Cuban Revolution, Afghanistan War and Vietnam War. A guerrilla army may increase the cost of maintaining an occupation or a colonial presence above what the foreign power may wish to bear. Against a local regime, the guerrilla fighters may make governance impossible with terror strikes and sabotage, and even combination of forces to depose their local enemies in conventional battle. These tactics are useful in demoralizing an enemy, while raising the morale of the guerrillas. In many cases, guerrilla tactics allow a small force to hold off a much larger and better equipped enemy for a long time, as in Russia's Second Chechen War and the Second Seminole War fought in the swamps of Florida (United States of America). Guerrilla tactics and strategy are summarized below and are discussed extensively in standard reference works such as Mao's "On Guerrilla Warfare."