This text is considered foundational to international relations, in defence of the theoretical model of realism, which was subjected - after the end of the Cold War, the collapse of the Berlin Wall, and the disintegration of the Soviet Union - to heavy criticism, glorifying what they described as "the triumph of Western liberalism" and beginning an academic debate on the value of realist theory to the field. The value of this text comes from its author, Kenneth Waltz, who is considered the founder of structural realism and who established this theory through his formative book Theory of International Politics (1979), which is considered the most influential IR work of the Cold War era. In this text, Waltz responds to the criticism levelled at realism, demonstrating its capacity to interpret in spite of changes in the structure of the international system.