The end of the US’s pre-eminence in the international political system has long been foretold. Since the collapse of the Soviet Union at the beginning of the 1990’s, the US has enjoyed a period of undisputed supremacy in international politics. Yet throughout this ‘unipolar moment’, many different factors have been cited as indicators of the gradual US decline. These have included the spiralling costs of the war on terror and the 2008 global financial crisis. However, does the recent debacle over military intervention in Syria represent the ‘true’ end of US hegemony in the international political system as we know it?
US President Barack Obama’s attempts to build an international consensus on multilateral military intervention in Syria were widely seen as an abject failure. For many, Russian President Vladimir Putin roundly outmanoeuvred Obama through his much lauded ‘political solution’ which advocated the supervised destruction of Syrian chemical weapons as opposed to military intervention. Whilst Forbes’s recent naming of Putin above Obama as the current most powerful person in the world is questionable, it is reflective of a solidification in the perception of a wider decline in the US’s relative presence and influence on the world stage. Regardless of the exact applicability of this assessment, it is apparent that in many ways the recent Syria debacle represents the nadir of US global leadership in recent times.
The failure of the US to achieve its aim of intervention in Syria is extraordinary in many ways. There are arguably two components to hegemonic leadership: firstly, the maintenance of a wide sphere of influence within which the hegemon has exclusive power and control; and secondly, the ‘hard’ military and economic capabilities that enable this projection and exclusivity of power. AS the most powerful nation on Earth, the US certainly fulfills the latter requirement. Regardless of its rise, China is yet to fully make the transition to a great power, and the US faces no other immediate competitors for supremacy. However, the Syrian question appears to have concerned the first component of US hegemony – the ability to maintain a sphere of influence such that no other state will challenge it.
Playing the ‘reluctant hegemon’, Obama’s reticence to act during international discussions on Syria was matched in size only by the lethargy of his eventual response. ‘This belated response itself was only precipitated due to his being committed politically to intervene due to his infamous ‘red line’. Additionally, despite not having shown any qualms with the exercise of his executive powers to wage war in the past with Libya, he buck-passed the issue of intervention to Congress – further weakening US leadership on the issue internationally. The direct challenge posed to the US’s global leadership by Russia, in spite of intense international pressure, is surely indicative of the degree to which this sphere of influence has been eroded.
Drawing on wider perceptions of a US decline, in a well-known 2009 Weekly Standard article Charles Krauthammer argues that ‘Decline is a choice’.  Krauthammer believes the timid and deferential approach to foreign policy adopted by the Obama administration to have directly contributed to a decline in US hegemony in the international political system. And thus, it is the actions (or inactions) of the Obama administration that have precipitated this decline.
Regardless of the debate about the exogenous versus endogenous factors in the decline of US hegemony, Krauthammer’s thinking is interesting when assessing the implications that this decline will have for the international political system. Krauthammer’s central premise follows constructivist notions on the nature of the international political system. Simply put, it is due to the actions of states and other actors in the international political system, which form or construct the international political system into what it is; it is not simply there. It is the interactions and the form these interactions take which result in the formation of the system and therefore the actions of states and of other actors that constitute the system in its entirety. As a social reality, it is inherently dynamic. Drawing on these notions, it follows that the very nature and character of the international political system itself is constructed by the hegemon. Linked to this, hegemonic stability theory posits that the hegemon actively maintains an international political system in its image, embedding certain normative frameworks and structures within it. As the closest actor to an independent guarantor of security in the international political system, it falls to the hegemon to maintain the stability of the system and the norms governing the ways states behave. From these standpoints, with the death of a hegemon before its time do we now face a crisis in the maintenance of the international political system?
According to hegemonic stability theory, through this maintenance the hegemon imposes order and stability onto an otherwise chaotic international political system. This represents a public good from which the system and all states benefit as a whole. Thus, a lack of hegemonic leadership represents a crisis in global governance as the various international regimes, which provide piecemeal and disconnected instances of rule-governed behaviour in an anarchic system, face possible collapse. This negatively impacts all states as inter-state interactions in the international political system become more opaque, engendering fear and uncertainty. Indeed, the US’s failure to fulfil the role of hegemon has already raised ire amongst members of the international community. Saudi Arabia’s recent stinging attack on the US and its unprecedented rejection of an American backed place in the UN Security Council is telling of perhaps wider international concern at the perceived shirking by the US of its international obligations. Without US maintenance, the international political system faces instability as it undergoes a period of adjustment and ‘post hegemonic rebound.’
This crisis in system maintenance also provides a prism for an exploration of the wider implications of a change in systemic polarity, an eventual inevitability with the rise of China and the BRIC states more widely. Francis Fukyama famously argued for ‘The End of History’ that the collapse of the Soviet Union signalled the ultimate triumph of liberal democracies. The Fukyaman international political system was overseen by the US and championed liberal democratic values. This was a period in which sovereignty underwent the greatest transformation, from its Westphalian origins through the norm of ‘sovereignty as responsibility’, in which the notion of humanitarian intervention saw greater normalisation and the UN’s Responsibility to Protect (R2P) was famously conceived. Moreover, it was ultimately the period in which a variety of cosmopolitan principles were codified at the heart of the international political system through the notion of liberal interventionism. The eventual arrival of a multipolar system will arguably see a dilution of these principles and a possible return to the principle of inviolable sovereignty, as no state will be willing, or able, to enforce these norms in a post-US hegemonic system. Indeed, the international interactions of China, possibly the strongest actor in the future political system, have a saliently non-interventionist character. Its dealings with states in Africa have been noticeably transactional and utilitarian, jarring with the conditionalities central to any Euro-American interaction with Africa.
With the rise of China and the BRICs pointing towards a slow march towards multipolarity, the end of the unipolar moment is an eventual inevitability. However, the recent debacle of US led military intervention in Syria has exposed a wider crisis in the immediate international political system. Without the leadership of the US internationally, the international political system faces a rudderless period of instability and politicking stemming from this sudden vacuum. In an international system constructed on precedent, the decline of US hegemony on account of its role in the Syrian civil war perhaps represents a preview of an oncoming multipolar world.
 Fukyama, Francis (1992) The end of history and the last man