This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. In order to relieve pressure on large urban agglomerations in developing countries, Agenda 21 recommends that policies and strategies should be implemented towards the development of intermediate cities which create employment opportunities for unemployed labour in rural areas and support rural-based economic activities. Sound urban management would be essential to ensure that "urban sprawl" did not expand resource degradation over an ever wider land area and increase pressure to convert open space and agricultural/buffer lands for development.