The history of language planning in Brazil, the only Portuguese speaking country in South America, is shown to have been decisively influenced at every critical moment by prevailing geopolitical interests. Sharing borders with nine out of the 11 countries that, together with it, make up the continent, Brazil has always been attentive to perceived threats to its national security, coming whether from the inside or from the outside. The question of preserving and propagating its national language across its territory was, right from the beginning, a matter of national security. Recent attempts to rid the Portuguese language of all foreign influences, notably borrowings from English, it is argued, must also be seen from this perspective.