The Cold War analysis of less-developed countries (LDCs) was focused on the East-West bipolar alliances and the place of LDCs in geopolitical strategy. LDCs were strategic pawns in the Big Power Cold War game. As international trade and international finance were increasingly used to expand and strengthen the Cold War alliances (especially but not exclusively on the western side), IPE scholars pursued the impact of economic relations generally on LDCs. Or, in the terms associated with Immanuel Wallerstein, they probed the relationship between Core and Periphery.
The IPE set of problems therefore expanded to encompass a critique of economic development, an analysis of neo-colonialism and imperialism, and a general study of Core-Periphery relations. Security and geopolitical issues were not excluded from this North-South analysis; they merely lost the privileged position that they enjoyed in traditional International Relations research. In recent years, IPE scholars have focused on sustainable development, the reasons why failed states have formed, and how the rise of the BRICs (Brazil, Russia, India, and China) is reshaping North-South relations.