Ensuring national food security is a vital concern of all governments. Until the early 1990s, the Government of Bangladesh aimed to achieve food security by following a policy of self-sufficiency (growing within the country all the food the country needs). In 1993, however, the policy was changed to one of self-reliance (importing food from the world market when prices are cheaper than growing it at home, so as to release land for other uses for which Bangladesh has a comparative advantage).