What is the ‘Thucydides trap’ Xi warned Trump about? Lessons from an ancient war between Athens and Sparta

During their high-stakes meeting in Beijing this week, Chinese President Xi Jinping reportedly asked US President Donald Trump if the two countries could overcome the “Thucydides trap”.

This phrase, popularised by contemporary US political scientist Graham Allison in the early 2010s, is used to describe how two countries can drift toward war when an existing superpower feels anxious about an emerging one. Allison had China and the US in mind specifically.

It takes its name from Athenian historian and general Thucydides, who wrote the History of the Peloponnesian War, about the 27-year war between Athens and Sparta that broke out in 431 BCE.

But what did Thucydides really say on this? And what do Athens and Sparta have to do with the current state of US–China relations?

An implied fumble

The implication in the term “Thucydides trap” is that the established superpower manages the rising power badly and feels obliged to go to war when that’s not necessarily the only option.

It is based on a quote from Thucydides’ History of the Peloponnesian War (book one, chapter 23). He said:

The growth of the power of Athens, and the alarm which this inspired in Lacedaemon [Sparta], made war inevitable.

In other words, Thucydides is saying what made the Peloponnesian War inevitable was the rise of Athenian power.

At the time, lots of Greeks were saying Athens and Sparta had gone to war again because of smaller disputes.

But Thucydides says no, the real cause was the overall fear that Sparta (the traditional superpower) had for the new powerful state: democratic Athens.

The general idea, of course, is that in its anxiety about the rise of China, the US may tend toward war when other options are available.

But many scholars of ancient Greece take issue with the way the term is used today.

A contested term

The word “trap” implies Sparta made a mistake in 431 BCE and could’ve handled things better. But that’s not what Thucydides really narrates in book one of his History of the Peloponnesian War.

He shows that, in fact, Sparta had good reason to fear the rising Athenians. Athens was, by then, a predominate naval power in the Balkans and the Aegean Sea. It was stripping allies off Sparta left, right and centre, and beating up the ones that refused to defect.

Those allies basically said to Sparta in 432 BCE: listen, you have got to do something about Athens and if you don’t act, we will join them.

It was pressure from these allies that pushed the Spartans to act against Athens.

So yes, in a sense Sparta’s own anxieties about ever-increasing Athenian power led to war. Sparta felt compelled to wage total war against Athens to maintain its system of alliances, and in 431 BCE broke the peace treaty it had with Athens.

A longer-term perspective

More generally, the term “Thucydides trap” is about how over the longer term things didn’t turn out so well for Sparta; although they won the Peloponnesian War, it took them 27 years to do so.

And after the victory, Sparta engaged in a huge expansion to become an even greater superpower. That ended up making all the other Greeks very fearful for their security. This growth in Spartan power after 404 BCE caused many of its allies to become enemies. All those Greek states then came together to confront Sparta, which was completely and utterly destroyed in 371 BCE at the Battle of Leuctra.

The whole security architecture of Sparta collapsed; they lost all their allies, all their slaves were liberated and Sparta was reduced to just a minor state.

So the lesson for the US implied in the term Thucydides trap is that fear of superpowers is a potent shaper of international affairs.

But many people who use the term Thucydides trap forget to mention what happened to Athens in the longer term.

Athens survived the Peloponnesian War and restored its democracy and military, and became a regional power. But what’s fascinating is that by the early 4th century BCE Athens was under immense pressure from the Persian empire, which was many times more powerful than any Greek state.

So Athens clipped its own wings and gave up on being this huge Mediterranean superpower; it decided to forego any attempt to reassert its imperial control over the many Greek states of Anatolia, allowing them again to be subjects of the Persian empire.

Athens decided to focus more closely on the Aegean Sea and give up on fighting Persians; it recognised the constraints of its power.

So it’s not as though Sparta’s decision to enter war with Athens in 431 BCE led, in the long run, to total world domination by Athens.

A lesson for today

The history of the Peloponnesian War provides important lessons for China–US relations today.

One is that it may be foolish for an established superpower to check the rise of an emerging one. Sparta learned that trying to do so can come at a terrible cost.

Accommodating Athens would have allowed Sparta to continue as a superpower well into the fourth century.

Another lesson is that an established superpower, such as the US, can cut back its ambitions and focus on regions closer to home.

This is exactly what democratic Athens did after the Peloponnesian War. Doing so allowed it to flourish culturally and politically and keep enemies well away until the 310s BCE.