 Historical experience, in Nielsen’s view, tells us that terrorism on a small scale, used as the sole method of struggle in order to provoke the masses into revolutionary action, is ineffective and often counterproductive. On the other hand, terrorism employed in conjunction with guerrilla warfare in a protracted war of liberation may well prove useful and therefore also justified, as it did in Algeria and South Vietnam. (For an earlier statement of the same view, see Trotsky 1961: 48–59, 62–65.)