The governments of virtually every country on the planet attach great importance to achieving food security and a wide variety of mechanisms have been developed to realize this goal. The first issue governments face in achieving national food security is the problem of insuring that adequate amounts of food are available to the resident population. Some governments have set goals of food self-sufficiency, which means most if not all of the food available in a country comes from the domestic farming system. However, food security does not require food self-sufficiency because countries can import food items not easily produced within the country. Agricultural products are, after all, highly sensitive to climatic, soil and other conditions that tend to vary around the world. Even countries with extremely productive agricultural sectors are not fully self-sufficient in all food items. The United States, for example, depends on imports for its supply of coffee, tea, bananas and other tropical products. In general, the problem of assuring adequate food supplies is solved by relying on both domestic production and imports.