Because of the non-inevitability of communist revolution, communism has been imposed on certain countries where the opportunity for violent revolution arose. Nationalism is denied in strict communist doctrine, but is applied imperialistically by the dominant power under the guise of 'international communism'; that is, it imposes its national system on the countries over which it has control. This control may be politically or economically based. Attempts at national self-determination may be suppressed militarily (invasion, maintenance of military bases, control over secret police, the army) or they may be frustrated by economic dependence.