A lack of space for a race's growth would lead to its decay through degenerate population control methods and dependence upon other nations' imports. Expansion is directly correlated to the race's vitality, space allowing for larger families that would repopulate the nation from the losses it incurs fighting wars for territory. Where Hitler's expansionism differed most from that of imperial nations was his idea of racial purity, which required driving out or exterminating the native populations of any conquered territory. Industry and trade were only transient solutions, subject to the vicissitudes of the market, likely leading to war as economic competition escalates. Lebensraum was thus the only permanent solution for securing the German race's vitality. Colonies would take far too long to solve the Reich's agriculture and space problem; furthermore, they constitute a naval and industrial policy rather than a land-based agricultural policy, which is where Germany's strength lies. Thus, Hitler committed Germany to a role as a land power rather than a sea power and focused his foreign policy on attaining the highest possible concentration of land power resources for a future that lay in Europe.