We thank the Secretary-General for his clear and comprehensive report ( A/57/172 ) to the General Assembly on the implementation of the recommendations made five years ago in his report on `` Causes of conflict and promotion of durable peace and sustainable development in Africa '' . We also wish to thank him for the report ( A/57/156 ) on the detailed evaluation of the United Nations New Agenda for the Development of Africa in the 1990s ( UN-NADAF ) and on the obstacles that hindered its implementation .