The period after the Cold War marked a major shift in global power. The collapse of the Soviet Union in 1991 ended the decades-long rivalry between the USSR and the United States, giving rise to what Charles Krauthammer called the “unipolar moment”.^[1] It represented the geopolitical structure in which the United States became the undisputed pole of global power, attended by its Western allies.^[2] This dynamic began to change in the late 2000s, leading some to call it the return of the “great power competition”.^[3] By the mid-to-late 2010s, a new consensus formed: the US-led world order was being replaced.^[4] Today, the debate continues about what has succeeded the U.S. hegemony, but almost everyone agrees the “unipolar moment” has ended.^[5] This essay will discuss how this shift emerged. It will do so by analysing key assumptions and events from the decade that accelerated the collapse of the US-led global order. This essay argues that the end of the unipolar moment and the return of great power competition resulted from a combination of American strategic overreach and retrenchment, destabilising global crises, and the growing economic and military power of revisionist states, which collectively undermined the foundations of the US-led international order.

War, Retrenchment, and Unforeseen Crises

It is first crucial to examine policy choices by various U.S. administrations that came to be interpreted as “American hubris and overreach”.^[6] George W. Bush’s ambitious doctrine raised the initial questions related to America’s “imperial overstretch”.^[7] The four main tenets of the Bush Doctrine are: “a strong belief in the importance of a state’s domestic regime in determining its foreign policy, and the related judgment that this is a time of great opportunity to transform international politics; the perception of great threats that can be defeated only by new and vigorous policies (most notably preventative war); a willingness to act unilaterally when necessary; and, as both a cause and a summary of these three elements, an overriding sense that peace and stability require the United States to assert its primacy in world politics”^[8]. The Bush Doctrine combined a global war on terrorism with a strong assertion of American primacy. Bush’s vision focused on the “war against terrorists of global reach” and aimed to limit the actions of states actively seeking weapons of mass destruction.^[9] After the 9/11 attacks, the Bush administration mobilised American hegemonic power to strike al-Qaeda leadership and infrastructure in Afghanistan and destroy the Taliban regime – framing it as part of the Global War on Terror.^[10] On 7 October 2001, the Bush administration launched military operations in Afghanistan, initially targeting al-Qaeda training facilities and Taliban military installations.^[11] U.S. military expenditure expanded significantly during the post-9/11 period, increasing at a compound annual growth rate of approximately 9.8 per cent between 2001 and 2009.^[12] Analysis suggests that the conflict in Afghanistan was one of the key driving factors for increased U.S. military expenditure.^[13] In 2002-2003, the administration pivoted to destroy Saddam Hussein’s regime in Iraq as the next phase of the global “war on terror”.^[14] President Bush articulated a strategy centred on Weapons of Mass Destruction (WMD), emphasizing the need to “respond to the effects of WMD use against our forces abroad, and to help friends and allies if they are attacked.”^[15] Today, it is acknowledged that the strategy of unilateral primacy has not led to sustainable results and that both ventures failed to achieve long-term political goals.^[16] Incidents such as torture in American detention facilities and intelligence-gathering in the context of counter-terrorism was sanctioned by top officials, and damaged America’s global image extensively.^[17] Some, like Löfflman, labelled the Bush doctrine as “neo-imperial”.^[18]

Secondly, Dueck contends that Obama’s focus on domestic concerns, coupled with a low-cost grand strategy, exposed U.S. interests overseas to greater risk and contributed to a decline in America’s ability to preserve its global hegemonic status.^[19] Obama aimed to reduce the financial and military burdens of American hegemony by adopting a strategy of eliminating  suspected terrorist targets through drone strikes, raids carried out by U.S. special forces, and generally favoured a “light footprint” approach. This positioned the U.S. as a key network power in coordinating global governance, and less as a sole hegemon.^[20] The Arab Spring is worth calling out as a pivotal event during Obama’s two terms in office. It accelerated the move toward multipolarity by drawing more regional and global powers into a contest for influence in the Middle East. When the movement gained momentum across North African autocracies in 2010, Vali Nasr, who worked at the State Department between 2009 and 2011, highlighted the dilemma: “[Obama] did not know whether the Arab Spring would lead to ubiquitous democracy or a prolonged period of instability, but regardless, he was determined that America would not try to influence the outcome”.^[21] Overall, Obama’s focus on domestic affairs has positioned him among the country’s great progressive presidents.^[22] However, his prioritisation of domestic challenges over large-scale foreign engagement reflected growing public fatigue with overseas interventions and contributed to perceptions of a more restrained American global role.  

Thirdly, an unexpected turning point for the US-led post-Cold War order was the 2008 Global Financial Crisis (GFC). The interconnected global economy, large balance sheets, and rising leverage created shared vulnerabilities.^[23] The GFC severely damaged the appeal of the American economic model and underscored a shift of economic power eastward, especially toward China.^[24] Adam Tooze linked deep private financial integration to the GFC spilling into international relations.^[25] He argued that economic and political questions triggered by the crisis were posed in a geopolitical force field instead of a power vacuum, as graphically evidenced by subsequent Russian aggression in Georgia and Ukraine. Such actions by Russia indicated that the old American rival increasingly challenged U.S. dominance through military intervention and coercive foreign policy. Reflecting a broad conventional view, some foreign policy commentators said that after 2008, the “end of history” was replaced by the “end of America”, “triumphalism” gave way to “declinism”, and the post-Cold War utopia shifted to a “post-American” world.^[26]

Competition for Influence and the Return of Great Power Politics

The final metanarrative seeking to explain the end of the ‘unipolar’ moment demands revisiting an old concept: the rise of a hostile Eurasian hegemon. In 2014, Robert Kagan argued that such an event could ultimately threaten the U.S. security interests and economic well-being.^[27] Three months prior, Russia had invaded Crimea, resetting Russo-American relations to something near a Cold War climate, and, by extension, raising serious questions about NATO’s ability to honour its existing commitments on its Eastern flank.^[28] Beyond soft sanctions, diplomatic isolation, and resistance to providing substantial military aid to Ukraine for fear of escalation, the response to Crimea’s annexation taught Moscow that territorial expansion by force in Europe would not elicit a decisive response from Washington and its Western allies. Putin later applied this lesson learned by embarking on a full-scale invasion of Ukraine in 2022 and launching the deadliest European conflict since World War II. 

Also in Eurasia, China averaged approximately 10 percent annual growth since 1979, doubling its economy every eight years, and surging past Japan as the second-largest economy globally by the mid-point of Barack Obama’s presidency.^[29]The question then became when, not whether, Beijing would outpace Washington economically. China’s economic growth translated into its military might, and Chinese defence capabilities grew approximately sevenfold between 1996 and 2013.^[30] During the 1990s, President Bill Clinton decided to “midwife” China into globalisation by encouraging Beijing to join the World Trade Organisation. Beijing continued to pursue its dominance in Asia and the Western Pacific and embarked on a competition for influence across Latin America and Africa.^[31] In 2013, China’s Belt and Road Initiative was announced – the largest single infrastructure project since the Marshall plan.^[32] A prominent example is the construction of Chancay megaport in Peru, set to reshape maritime trade in South America. Upon completion, the port would make Peru a distribution centre in the Pacific and connect it with the American Atlantic coast.^[33] Multiple Latin American countries currently host projects controlled and developed by Chinese companies. Since 2015, there have also been new investments in the telecommunications and energy sectors across Latin America, including submarine cables and 5G networks.^[34] More broadly, the emergence of BRICS (Brazil, Russia, India, and China) marked a significant shift in global dynamics. Originally coined by Goldman Sachs economist Jim O’Neill in 2001^[35], the term later evolved into a formal political grouping, culminating in the first BRIC summit in 2009.^[36] According to O’Neikk, the decision by Russia to call a convening of the four countries was driven by President Putin’s desire to counterweight the West.^[37]All countries combined represented more than 25 percent of the world’s land area and almost half of the world’s population, traded increasingly with each other, and explored pathways for political cooperation.^[38] As a bloc composed of liberal democracies and illiberal regimes, BRICS countries have remained ambivalent about liberal democratic values, as illustrated by such cases as repression of Muslim communities in China, where “an estimated one million Muslim people have been detained in camps and prisons in Xinjiang, Northwest China” as of 2019.^[39] The group has also identified a set of priorities aiming at reducing reliance on the U.S.-led global system through economic means, for example by reducing reliance on the U.S. dollar, and creating an alternative finance system through such initiatives as the group’s New Development Bank and Contingent Reserve Arrangement.^[40]

In 2017, the U.S. national security strategy officially accepted the “return of the great power competition” to the global political debate: According to the document, “…after being dismissed as a phenomenon of an earlier century, great power competition returned. China and Russia began to reassert their influence regionally and globally”.^[41] As such, President Trump signposted the final phase in the transformative decade which marked the end of America’s hegemony. Yet it would be unjust to attribute the crisis of world order solely to American policy decisions. The absence of a “peer competitor”^[42] was unlikely to ever become an enduring status quo in the global arena. Technological advancement and globalisation made it extremely difficult for any country, of any stature and sinew, to prevent competitors, including those traditionally considered weaker, from developing the various realms of power in the context of the modern global order. In other words, asymmetric competition and challenges to American hegemony may have been unavoidable. Even if such elements of power are insufficient for any state to become the next hegemon, actors traditionally considered rogue, poor, or weak enjoy a previously unseen capacity to challenge their more powerful rivals through technology-enabled means such as hybrid attacks, cheap modern weaponry, and cognitive warfare. For example, the VIGINUM report on the “Portal Kombat” network examines this transformation by describing a coordinated system of almost 193 so-called “information portals” disseminating pro-Russian narratives across multiple countries which openly expressed support to Ukraine, including France, Germany, Austria, Switzerland, Poland, Spain, the United Kingdom and the United States.^[43] Whereas the Russian-sponsored interference campaign targeting the 2016 US Presidential Elections had no military component and at the same time turned the very features that were supposed to enhance the US structural (cyber) power against itself.^[44]  

Conclusion

The everchanging global order interrogates whether the pursuit of world stability is a vague aspiration or an incomplete, but feasible project.^[45] The above analysis did not attempt to answer such broad questions. The central argument of this analysis, however, is that certain American policy decisions, such as President Bush’s “imperial overstretch” and President Obama’s focus on domestic policies, have contributed to the erosion of U.S. dominance and the end of the “unipolar moment”. This decline was compounded by unpredictable crises, rapid technological progress worldwide, and shifts in competitors’ behaviour. To some, the end of unipolarity may reflect the American State’s need to address urgent domestic challenges. To others, it may rather represent a rebalancing of privilege in the international system. Finally, traditional and emergent adversaries of the West may see here an opportunity to promote “multipolarity”, relegate the status of the U.S. to that of a regional power, and subsequently pursue their long-term expansionist goals in their so-called “spheres of influence”. As contemporary observers grapple with labelling the newly emerged state of international affairs, questions remain about whether a stable and predictable world order is possible and, if so, what principles, if any, it ought to adhere to.^[46] Whether law, cooperation, or simply “balance of terror” ^[47] provides the most durable foundation for a desired order remains an open –and deeply contested– question. 

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^[1] Charles Krauthammer, “The Unipolar Moment,” Foreign Affairs 70, no. 1 (1991): 23–33, 23.

^[2] See footnote 1.

^[3] The Center for a New American Security, “Remarks by Defense Deputy Secretary Robert Work at the CNAS Inaugural National Security Forum,” December 14, 2015, https://www.cnas.org/publications/transcript/remarks-by-defense-deputy-secretary-robert-work-at-the-cnas-inaugural-national-security-forum.

^[4] Christopher Layne, “This Time It’s Real: The End of Unipolarity and the Pax Americana,” International Studies Quarterly 56, no. 1 (2012): 203–213, 203.

^[5] Foreign Affairs, “Did the Unipolar Moment Ever End?” Foreign Affairs Asks the Experts, May 23, 2023.

^[6] Hal Brands, Making the Unipolar Moment: U.S. Foreign Policy and the Rise of the Post–Cold War Order (Ithaca, NY: Cornell University Press, 2016), 358.

^[7] Robert Jervis, American Foreign Policy in a New Era (London: Routledge, 2005), 110.

^[8] Robert Jervis, American Foreign Policy in a New Era (London: Routledge, 2005), 79.

^[9] The White House, The National Security Strategy of the United States of America (Washington, DC, 2002), https://georgewbush-whitehouse.archives.gov/nsc/nssall.html.

^[10] Ibid.

^[11] George W. Bush Presidential Library and Museum, Global War on Terror (Dallas, TX: George W. Bush Presidential Library and Museum), https://www.georgewbushlibrary.gov/research/topic-guides/global-war-terror.

^[12] Stockholm International Peace Research Institute, SIPRI Yearbook 2010: Armaments, Disarmament and International Security (Oxford: Oxford University Press, 2010), Table 5A.4, “Military expenditure by country, in constant US dollars for 2000-2009 and current US dollars for 2009”.

^[13] Ibid., 196-197.

^[14] Brands, Making the Unipolar Moment, 357.

^[15] See footnote 9.

^[16] Georg Löfflmann, “The Bush Doctrine Redux: Changes and Continuities in American Grand Strategy since ‘9/11’,” International Politics 61 (2024): 501–522, https://doi.org/10.1057/s41311-023-00461-9.

^[17] Philip S. Golub. “Imperial Politics, Imperial Will and the Crisis of US Hegemony.” Review of International Political Economy 11, no. 4 (2004): 763–86, 780. http://www.jstor.org/stable/4177521.

^[18] See footnote 16, 501.

^[19] Colin Dueck, The Obama Doctrine: American Grand Strategy Today (Oxford: Oxford University Press, 2015), 104.

^[20] Georg Löfflmann, “The Bush Doctrine Redux: Changes and Continuities in American Grand Strategy since ‘9/11’,” International Politics 61 (2024): 513, https://doi.org/10.1057/s41311-023-00461-9.

^[21] See footnote 19, 76. 

^[22] Colin Dueck, The Obama Doctrine: American Grand Strategy Today (Oxford: Oxford University Press, 2015).

^[23] David Miles, “Review of Crashed: How a Decade of Financial Crises Changed the World,” Business Economics 54 (2019): 257–259, 257, https://doi.org/10.1057/s11369-019-00140-9.

^[24] Brands, Making the Unipolar Moment, 359.

^[25] Adam Tooze, Crashed: How a Decade of Financial Crises Changed the World (London: Penguin Random House, 2019), 609.

^[26] Robert Kagan, “Superpowers Don’t Get to Retire,” New Republic, May 26, 2014, https://newrepublic.com/article/117859/superpowers-dont-get-retire.

^[27] Ibid.

^[28] Brands, Making the Unipolar Moment, 359.

^[29] Brands, Making the Unipolar Moment, 360.

^[30] See footnote 28.

^[31] Brands, Making the Unipolar Moment, 359.

^[32] University of Cambridge Institute for Sustainability Leadership, China’s Belt and Road Initiative: Sustainability in the New Silk Road (Cambridge, June 2022), https://www.cisl.cam.ac.uk/files/chinas_belt_and_road_initiative090622_en.pdf.

^[33] Vice Admiral Ignacio Mardones, “Chinese Investment in Peru Set to Reshuffle Maritime Trade in South America,” Royal United Services Institute (RUSI) (London, November 15, 2022), https://www.rusi.org/explore-our-research/publications/commentary/chinese-investment-peru-set-reshuffle-maritime-trade-south-america.

^[34] Ibid. 

^[35] Anshu Siripurapu and Noah Berman, “What Is the BRICS Group and Why Is It Expanding?” Council on Foreign Relations (New York, June 26, 2025), https://www.cfr.org/backgrounders/what-brics-group-and-why-it-expanding.

^[36] Peter Lowe, “The Rise of the BRICS in the Global Economy,” Teaching Geography 41, no. 2 (2016): 50–53, https://www.jstor.org/stable/26455170.

^[37] Ibid. 

^[38] Ibid. 

^[39] Amnesty International UK, “China’s Uyghur Muslims: The Truth Behind the Headlines” (London, n.d.), https://www.amnesty.org.uk/knowledge-hub/all-resources/chinas-uighur-muslims-truth-behind-headlines/.

^[40] Anshu Siripurapu and Noah Berman, “What Is the BRICS Group and Why Is It Expanding?” Council on Foreign Relations (New York, June 26, 2025), https://www.cfr.org/backgrounders/what-brics-group-and-why-it-expanding.

^[41] The White House, National Security Strategy of the United States of America (Washington, DC, December 18, 2017), https://trumpwhitehouse.archives.gov/wp-content/uploads/2017/12/NSS-Final-12-18-2017-0905.pdf.

^[42] Brands, Making the Unipolar Moment, 10.

^[43] VIGINUM, Portal Kombat: A structured and coordinated pro-Russian propaganda network (Technical report, February 2024), 5.

^[44] Maschmeyer, Lennart. “Subversion, Cyber Operations, and Reverse Structural Power in World Politics.” European Journal of International Relations 29, no. 1 (2023): 79-103. https://doi.org/10.1177/13540661221117051.

^[45] John Bew, “World Order: Many-Headed Monster or Noble Pursuit?” Texas National Security Review 1, no. 1 (December 2017): 14-35, 34, https://tnsr.org/2017/11/world-order-many-headed-monster-noble-pursuit/.

^[46] Andrew Ehrhardt, “The Philosophical Aspect of World Order,” International Affairs 99, no. 4 (2023): 1741–1753, 1752, https://doi.org/10.1093/ia/iiad117.

^[47] Tooze, Crashed, 616.