In summary, two endogenous structural elements of the Cuban system condition each other reciprocally and are apparent even today: a form of centralized government controlling everything and the predominance of extensive and inefficient forms of production. When, at the beginning of the 1990s, the subsidy flowing in from fraternal socialist assistance was cut off, Cuba lost 75 percent of its foreign trade and, by the same token, its economic base. The former guarantor of Cuba's development-the fundamental economic link with the Soviet Union - turned out, in the end, to be a Janus head, and the Revolution sank into the most acute crisis in its history. The legacy of this experience was an oversized and inefficient economy incapable of surviving without enormous volumes of input and, moreover, specialized in the export of a few raw materials, such as sugar and nickel, and practically estranged from the world market. This abrupt collapse in foreign trade can, therefore, be seen as a first exogenous structural element associated with the transformation. To this must be added the effects of the U.S. blockade, which may merit the distinction of being the last institutionalized conflict to have survived the cold war. Notwithstanding the international easing of tensions, the United States has stepped up its confrontation with Cuba. The passage of the Helms-Burton Act in 1996 strengthened the blockade in addition to giving it an extraterritorial dimension. Therefore, the U.S. blockade must be considered as a second exogenous structural element of the Cuban transformation.