‘Increasingly’, wrote historian Charles Maier in the aftermath of the 9/11 attacks, ‘Americans talk about themselves, and others talk about America, as an empire’ (2002: 28). The wars in Afghanistan and Iraq coincided with an explosion of interest in the United States as an imperium (Cox 2003; Mabee 2004; Nexon and Wright 2007). Critical scholars had long grappled with the (neo-)imperialist characteristics of US foreign policy. Many sought to place the unilateralist militarism of Bush in a broader historical setting, while also connecting the evolution of US policy to the global capitalist economy (Colás and Saull 2006). On the right, some commentators began calling for a more robust American imperialism (Ferguson 2004). Occasionally, they were supported by liberals who saw empire as a path to humanitarian intervention (Ignatieff 2003). More often, liberals were sceptical of this imperial turn, viewed as a departure from the prudential tradition of American statecraft (Ikenberry 2002). Meanwhile, many neoconservatives advocated the unbridled application of American power while rejecting the proposition that the United States was, in fact, an empire (Krauthammer 2002/3). This denial was shared by policymakers, who argued that the United States had ‘no empire to extend or utopia to establish’, in the words of President Bush (2002). The debate shifted as neoconservative hubris gave way to declinist anxieties and concerns over imperial overstretch. In a flash, the United States saw its unipolarity dissolve from definitive fact to speculative proposition.