From the 1960s, developing countries actively pursued the implementation of the principle of permanent sovereignty over natural resources because they perceived this to be a main basis for their economic development and for a redistribution of wealth and power in their relations with the industrialized world. Consequently, during the period 1963–70 emphasis on State control and the actual ways of implementing the principle of permanent sovereignty over natural resources increasingly received attention and the link between permanent sovereignty over natural resources and promoting the development of developing host countries was firmly established. General Assembly Resolution 2158 (XXI), in particular, was instrumental in this, both substantively and politically. The guidelines it entails for the relationship and co-operation between foreign investors and developing host countries contain a relevant and substantive inventory of the problems involved and recommend constructive policies. Politically, it was important that the broad coalition which supported the 1962 Declaration persisted.

Yet, after 1970 the discussion on permanent sovereignty over natural resources changed substantially. Some controversial elements were more vigorously introduced in the discussion on the scope and content of permanent sovereignty, in particular creeping jurisdiction of coastal States over adjacent sea areas and marine resources which often led to fishery disputes, and the issue of economic coercion. Furthermore, in the early 1970s an increasing number of developing countries nationalized certain sectors of their economies, including foreign-owned sectors, and sought international legitimization for these actions through the United Nations leading to a resumption of the ‘nationalization debate’.