The ‘Thucydides Trap’ is a term coined by Harvard professor Graham Allison to ostensibly describe the tensions and conflict that occur when an existing great power is confronted with a rising state. According to Allison, as the new power rises, the two are more likely to engage in violent conflict as the new power displaces the old. He cites sixteen cases of power transition since the late 15th Century, of which twelve resulted in war between the two powers. Allison also cites Thucydides, and in particular the ancient Athenian author’s conclusion that the war between Athens and Sparta, chronicled in his History of the Peloponnesian War, began:
“…because they [the Spartans] were afraid of the further growth of Athenian power.”
Allison argues that the United States and China now face a Thucydides Trap scenario, as rising Chinese power challenges US hegemony. His thesis is evocatively outlined in his recent book, Destined for War. Allison’s ‘Thucydides Trap’ concept, however, is deeply flawed. Allison misinterprets Thucydides and his conception of power, and ignores important nuance in his analysis of the sixteen cases he considers, and thus comes to potentially incorrect conclusions on the Sino-US relationship and the likelihood for war. Instead, conflict is likely to occur between powers only when one power has expanded its territory aggressively against other states. Military expansionism, not merely a change in the balance of power, is the trigger for Thucydides Trap.
Allison begins his assessment of the Sino-US Thucydides Trap by describing China’s meteoric economic and geo-political rise over past 30 years. He notes, according to the International Monetary Fund (IMF), China is now the world’s largest economy, and China has passed the US in other indicators, such the production of ships, steel, and computers, and the consumption of automobiles and cell phones. Since the Global Financial Crisis in 2008, China has been world’s primary engine of growth. China is a powerhouse of construction and technological investment. China has also similarly grown in military power, with new focuses on military reform and new platforms. According to a 2015 RAND study, China now has advantage or parity with the US in six of nine areas of military capability. China’s economic and military growth has been translated into new assertiveness in foreign policy to pressure other countries to follow its lead. Thus, Allison concludes that China is increasing in power relative to the US. This may be true using a modern definition of the word ‘power’, but it is not a definition that Thucydides would have used.
In The Pentecontaetia, Thucydides describes Athens’ rise following the Persian War, but little attention is paid to growth in Athenian strategic capabilities. There are only two instances where Thucydides cites a material increase in Athenian capabilities – the building of walls around their new city, and growing naval dominance at the expense of ‘allies’. Most of The Pentecontaetia is instead devoted to describing growing Athenian dominance over its ‘allies’ in the Delian League, and military operations abroad. Following issues with their commanders, Sparta withdrew from leadership of the League in favour of Athens. The League was originally made up of independent city-states, but increasing Athenian control over it turned it into a de facto Athenian Empire. Thucydides then describes the evolving nature of alliances in Greece, and Athens’ increasingly audacious military operations, including conflict with Corinth over Megara, and a military intervention into Egypt. Thucydides seems to have firm numbers of ships and forces deployed in these operations, but does not include an overall number for Athens as a whole. This focus on alliance politics and actual military operations, rather than latent economic or military capabilities, stands in contrast to Allison’s description of China’s rise.
As tensions between Sparta and Athens escalate, the Spartans hold a conference of their allies, including Corinth, to decide a course of action. During the meeting, Athenian representatives, as recorded by Thucydides, actually reference what they believe is their growth in ‘power’ as the growth in their imperial control, not economic or military capabilities. Thucydides does provide some descriptions of capabilities at the outset of the war, including a request by Sparta for its allies to provide 500 ships and two-thirds of their forces. He finally gives a detailed account of Athenian finances and military forces. Importantly, however, he gives these details while citing a speech made by the Athenian statesman Pericles, and makes no attempt to compare them to the forces or finances of Sparta. The only place where a clear comparison between Athens and Sparta is given is in the speech given by the Spartan King Archidamus against the war. The inclusion of these comparisons in a speech, rather than Thucydides own analysis, is telling. Even if Thucydides was not quoting Archidamus directly, he nonetheless did not want to appear to make such comparisons himself, or considered them important enough to have in his own analysis.
The only place where a clear comparison between Athens and Sparta is given is in the speech given by the Spartan King Archidamus against the war.
While it’s clear that Athenian power rose relative to Sparta in the time since the Persian Wars, Thucydides was most interested in coalescing Athens’ imperial-alliance system and its newfound military confidence. Unlike Allison, Thucydides pays little attention to the material capabilities of either Sparta or Athens, and does not compare the two. Instead he focuses on the extent of their alliances, making sure to outline what states were aligned to which power at the war’s outset, but not the strength of militaries. A Thucydidean definition of power then is not merely growth in economic, technological, or military capability, but a focus on influence and demonstrated power projection.
This interpretation actually provides a more nuanced understanding of the cases cited by Allison as Thucydides Trap scenarios. In focusing on the growth in relative capabilities in each case, Allison misses the more critical factor - state behaviour. In each case, Allison describes the changes in economic and military strength of each state to demonstrate the ‘rising’ power in contrast to the ‘ruling’ power. He also notes the immediate behaviour and precipitating conditions for conflict, and the conflicts themselves. Allison’s focus on the capability changes between the ruling and rising powers, however, overshadows the more important factor in determining whether or not conflict will occur - territorial expansion.
In eleven of the twelve cases that resulted in war, the rising power or both powers had expanded in territory, usually through violence, in the preceding years. In the remaining case, France and Great Britain in the late 17th to Early-18th Centuries, the ruling power, France, was the expanding power. In the case of the rise of England relative to the Dutch Republic in the 17th Century, England’s expansion was an assertion of sovereign control over the seas and ports, not land. In the four cases that did not result in war, territorial expansion either did not occur or was more of a proximate, rather than primary cause of conflict.
Portugal and Spain avoided war in the 15th Century even as Spain expanded because Spain’s major territorial expansion, the unification of Castile and Aragon, was peaceful and consensual. Its conquest of Grenada was of a small, Muslim state, and so far less threatening from Portugal’s perspective. Portugal’s main issue was with Spanish expansion into the New World. Concerned with the potential conflict, Spain sought mediation from the Spanish-aligned Pope Alexander VI. While Portugal rejected the Pope’s proposed solution, the suggestion formed the basis of the 1494 Treaty of Tordesillas, which divided territorial hemispheres at the 46th Meridian. Even though this case concerned Spanish expansion, from Portugal’s perspective the expansion wasn’t violent, as the one conquest was against an ‘illegitimate’ Muslim Emirate. While there was the real potential for conflict over claims in the New World, the extent and shape of the New World was largely unknown in 1494, and thus such expansion by either party remained entirely hypothetical.
The second case where war was avoided was between the rising power of the US and the ruling power of the United Kingdom in late-19th to early-20th Centuries. As American wealth grew over the 19th Century, so too did its foreign policy aspirations. In 1898 it fought against Spain principally over Cuban independence, freeing the colony from Spanish rule and seizing possessions elsewhere. Under the Presidency of Theodore Roosevelt, the US began to seriously enforce the Monroe Doctrine, seeking to limit the presence of European powers in the Americas. While President Roosevelt was a nationalist expansionist, most Americans were not. Instead America pursued a relatively benign policy of seeking dominance in the hemisphere, rather than actual expansion. The US confronted Britain over its boundary dispute with Venezuela, demanding it submit to neutral arbitration rather than simply bully Venezuela, and to saw off German imperial ambitions in the region. A boundary dispute over Eastern Alaska sparked tensions but was submitted to arbitration. While America certainly did expand territorially, violently in the case of Spain, the scale and manner was far less imperialist or confrontational than the standard of the time, and importantly did not clash with actual British security interests. While some in the UK were concerned about a future war with America, American expansion of influence and arbitrated confrontation with Britain stood in sharp contrast to the aggressive and confrontational expansion of Imperial Germany at the time.
While America certainly did expand territorially, violently in the case of Spain, the scale and manner was far less imperialist or confrontational than the standard of the time, and importantly did not clash with actual British security interests.
In both of the above cases, the potential costs of a war were no doubt also a factor in the avoidance of war. Both Spain and Portugal wished to avoid a repeat of the brutal War of Castilian Succession in the 1470s, and so were open to arbitration. US naval build-up had begun to alarm Britain, and it was recognised that while the US was weaker globally, it had a crucial advantage in naval operations in the Caribbean that Britain could not defeat. Nevertheless, it was the absence of clear territorial aggression against vital interests that avoided war. Without the danger of aggressive territorial expansion, the threat posed to the ruling power by the rising power was lessened, and the pressure to directly confront them lower.
The remaining two peaceful cases are modern. The Soviet Union’s challenge to America was precipitated by aggressive territorial expansion as it subjugated Eastern European countries into its sphere and fomented Communist expansion elsewhere. Allison himself argues that these conditions were enough for war between the US and Soviet Union, but it was prevented by the threat posed by nuclear weapons. Allison’s contention that the US and Soviet Union were not in conflict over the Cold War is also a bit of a stretch, and it should be noted that where conflict did occur, it was almost always over Soviet-backed Communist territorial expansion. The case of the rise of post-Cold War Germany to political prominence in the EU, at the expense of Britain and France, is also a case without aggressive territorial expansion. It is worth noting that it was Germany’s unification (and thus expansion) that most alarmed Britain and France in 1990.
Returning to Thucydides, we see a similar dynamic between Sparta and Athens. Over the period covered by The Pentecontaetia Athens growing control over the Delian League can be considered de facto imperial expansionism. Its operations in Egypt and then in defence of Corcyra can also be considered aggressive military actions.The fact that the war was largely precipitated by Corinthian territorial expansion against Epidamnus and Corcyra is also highly illustrative. Thucydides notes that during the Spartan debate over whether to declare war:
Most people’s views tended to the same conclusion – namely, that Athens was already acting aggressively and that war should be declared without delay [emphasis added]
The importance of this comment is the focus on Athenian actions, not capabilities, on Spartan thinking. A Thucydides Trap, if it exists, is thus defined not simply by a rising state’s growing capabilities relative to a ruling state, but by aggressive, expansionary behaviour, particularly by the rising power, and especially when that behaviour intersects with the ruling power’s security interests. In all of the cases surveyed by Allison that led to war, aggressive expansion by one party directly threatened or would have threatened the other’s security interests. In the cases that did not, expansion did not affect security interests or did not occur at all, except in the case of the US and Soviet Union, where the constraining factor was nuclear weapons. Capability growth in isolation does not create a Thucydides Trap, but only when it is joined with aggressive behaviour.
Applying this nuance to the modern case of the US and China, we see a clear link between increasing tensions and aggressive, territorial assertions by China, but also hope for peace. While China’s economic growth since the 1980s has been great, and its more recent military build-up significant, neither contributed to growing Sino-US tensions over that period. Peaks in tensions instead occurred around aggressive Chinese actions, such as the 1996 Taiwan Straits Crisis, when China threatened the independence of the breakaway state, or the collision between a Chinese MiG and US spy plane in 2001. If Allison’s thesis was correct, then tensions between the two powers should have grown commensurate with growing Chinese capabilities, rather than risen and fallen according to actions. Rather than stifle Chinese economic growth, the US helped facilitate it by normalising trade relations and supporting China’s joining of the World Trade Organisation in 2001.
If Allison’s thesis was correct, then tensions between the two powers should have grown commensurate with growing Chinese capabilities, rather than risen and fallen according to actions.
Tensions between the US and China grew significantly post-2009, the same time China began more aggressively asserting territorial claims in the South China Sea and East China Sea. In 2009 China issued its ‘9-Dash Line’ claim to the South China Sea, and began its land reclamation efforts and build-up around the Spratly Islands, and incidents of confrontation between Chinese vessels and others rapidly increased in number as it increased its claim of an economic exclusion zone around this area. The same is true of the East China Sea, where Japan and China dispute ownership over the Senkaku/Diaoyu Islands. Incursions into the waters by China were rare prior to 2011, but have surged in frequency since then. China’s territorial assertion led the US to respond with its ‘Pivot to Asia’ in late-2011, which included moving more US military forces to Asia. Since then tensions have increased, just as China has continued to assert dominance over its territorial claims and become more confrontational in asserting them.
Will these tensions lead to war? It will depend on how aggressively China asserts expansionary aspirations. Military annexations of Taiwan or the Senkaku/Diaoyu Islands are likely war triggers, but both are also unlikely. Keeping a lid on tensions is the high cost of a war to both parties, and the presence of nuclear weapons. In order to avoid war, China must avoid aggressive, territorially expansionist policies or military adventurism, while the US must allow peaceful, consensual Chinese expansion where possible, while also tolerating increased Chinese military and economic capabilities.
The ‘Thucydides Trap’ isn’t simply about a ruling power facing the growing economic and latent military power of a rising power. Instead, conflict is caused by the actual behaviour of the parties in question, and whether or not one of them, especially the rising power, aggressively asserts territorial claims. Doing so directly threatens the interests and perhaps integrity of the ruling power, either in the immediate or foreseeable future, and thus triggers conflict. Where no such aggressive expansion occurs, or it is caveated by other factors making it less threatening, no war occurs. Even where no war occurs, the peaks in tensions are around territorial growth, not general economic, technological, or military growth. Allison misinterpreted Thucydides, and thus has misunderstood the tensions between the US and China today, and the likelihood for war.
Declan Sullivan has just completed a Masters of Strategic Studies at the Australian National University and holds a Masters of Law from Texas Tech University. He has written for the Center for the National Interest and the Australian Strategic Policy Institute.
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Header Image: Kluge of a bust of Thucydides and a map of the Hellenic World.
 Graham Allison, Destined for War (NY: Houghton Mifflin Harcourt, 2017), xv.
 Thucydides, History of the Peloponnesian War, translated by Rex Warner, (NY: Penguin Classics, 1972), I.88, 87.
 Allison, Destined for War, xvii.
 Ibid, Chapter 1.
 Ibid, 10.
 Ibid, 9.
 Ibid, 12-15.
 Ibid, 16-19.
 Ibid, 20.
 Ibid, 20-24.
 Thucydides, History of the Peloponnesian War, I.89, 87.
 Ibid, I.93, 90.
 Ibid, I.99, 93.
 Ibid, I.94-I.96, 91-92.
 Thucydides, History of the Peloponnesian War, I.97-I.99, 92-93.
 Ibid, I.103-I.106, 95-97.
 Ibid, I.104, 96.
 Ibid, I.75, 79-80.
 Ibid, II.7, 128.
 Ibid, II.10, 130.
 Ibid, II.13, 132-133.
 Ibid, I.80-I.81, 82-83.
 Ibid, II.9, 129.
 Allison, Destined for War, Appendix 1.
 Allison, Destined for War, 249-251.
 Ibid, 51-52.
 Ibid, 245-246.
 Ibid, 94-96.
 Ibid, 92-93.
 Ibid, 97-98.
 Ibid, 102-104.
 Ibid, 197.
 Ibid, 272.
 Ibid, 246.
 Allison, Destined for War, 272.
 Ibid, 202.
 Ibid, 284.
 Thucydides, History of the Peloponnesian War, I.45, 62.
 Ibid, I.79, 82.