The issue of world order is central to an understanding of international politics. The shape of world order affects both the level of stability within the global system and the balance within it between conflict and cooperation. However, since the end of the Cold War, the nature of world order has been the subject of significant debate and disagreement. Early proclamations of the establishment of a 'new world order', characterized by peace and international cooperation, were soon replaced by talk of unipolar world order, with the USA taking centre stage as the world's sole superpower. This 'unipolar moment' may nevertheless have been brief. Not only did the USA's involvement in difficult and protracted counter-insurgency wars following September 11 strengthen the impression of US decline, but emerging powers, notably China, started to exert greater influence on the world stage. The notion that unipolarity is giving way to multipolarity has, moreover, been supported by evidence of the increasing importance of international organizations, a trend that is sometimes interpreted as emerging 'global governance'. Of particular importance in this respect have been the major institutions of global economic governance – the International Monetary Fund, the World Bank and the World Trade Organization – and the centrepiece of the global governance system, the United Nations. Although some argue that the trend in favour of global governance reflects the fact that, in an interdependent world, states must act together to address the challenges that confront them, others dismiss global governance as a myth and raise serious questions about the effectiveness of international organizations.