This book explains the development of the international system's present-day balance of power by exploring three central questions: (1) Under what conditions has the international system order evolved from a unipolar system to the current multipolar system? (2) What are its major states? (3) How do weak powers affect great power competition? It puts forward the following hypotheses: (1) if China and Russia are expanding their military, political, and economic influence into weaker states globally, then the unipolar American order is unraveling; and (2) if the international system is multipolar, then great power balancing may enhance international security. However, balancing may be made difficult because of weak state aid-seeking behavior. When weak states engage competing great powers, they become spheres of competition. This book delves into these states. Whether in Africa, Latin America, the Middle East, Central Asia, East Asia, or Eastern Europe, great powers hope to establish some control over weaker units for security, economic, and at times, prestige purposes. This book will be of interest to students and scholars of political science and IR, security studies, and IPE, as well as members of the think tank community and policy analysts.