Since the attacks on the United States of America on September 11th 2001 the US has chosen a strongly unilateral foreign policy underscored and effectively sustained by military power. In the immediate aftermath of the attack on the US it was speculated that American desire to build an international coalition against terrorism and to take military action in sensitive areas would lead it to engage in dialogue with its potential allies in both the developed and developing worlds. This did not prove to be the case as the US displayed a willingness to act in opposition to the international community and to back up its foreign policy decisions with force if necessary. This article analyses the current international role of the US and the impact US actions have on the emerging system of international governance. While the US is undoubtedly dominant, and their actions in the international arena have undermined the effectiveness of the United Nations, they have faced unprecedented opposition to their policy on Iraq, have not been able to prevent initiatives such as the International Criminal Court or to win widespread international support, in either the industrialised states or among the developing world for their actions. This indicates a reduction in US hegemony and also an increase in international insecurity as US foreign policy action aimed at securing a narrowing defined American national interest leads to growing polarisation in the international system.