As China surpasses the United States as the world’s largest economy, flexes its might in the South and East China seas, and takes a leading role fighting climate change, it appears to be on course to challenge America’s superpower status.  

Despite a seeming rapprochement over chocolate cake between China’s President Xi Jinping and President Trump in April, how the two countries navigate their strategic interests and work through China’s rise remains unclear. Is conflict inevitable when an upstart challenges a dominant power, or does history provide a road map for peaceful coexistence?

Graham Allison, the Douglas Dillon Professor of Government and outgoing director of the Belfer Center for Science and International Affairs at Harvard Kennedy School, calls this the defining question of the 21st century. In a new book, “Destined for War: Can America and China Escape Thucydides’ Trap?,” Allison examines the looming complications, using lessons drawn from the clashes between Sparta and Athens in ancient Greece, as well as other world conflicts. He spoke about his book and these issues in an interview.

GAZETTE: How would you characterize relations between China and the United States today as compared with, say, the 1970s under President Richard Nixon?

ALLISON: What most Americans still haven’t awakened to is that just in the last generation [China] has emerged like a rocket to displace the U.S. as the No. 1 producer of automobiles, computers, smartphones, and artificial intelligence. Indeed, it’s the largest economy in the world as measured by the best yardstick for comparing national economies: purchasing power parity. In the book, I illustrate this in terms of a seesaw, in which the U.S. is on one end and China is on the other. If you go back to 1990, China had about 15 percent the weight of the U.S. By 2014, China is roughly equal with the U.S., and by 2024 will be half again larger. So, just in our lifetime, a state that hardly mattered in international affairs and hardly mattered as a buyer or seller of anything has emerged as a serious rival and, in many arenas, has surpassed us.

GAZETTE: Can you explain Thucydides’ Trap? What prompted you to consider U.S.-China relations through this lens, and how does it help?

ALLISON: Thucydides’ Trap is the dangerous dynamic that occurs when a rising power threatens to displace a ruling power. That dynamic creates structural conditions in which events by third parties or accidents that would otherwise be inconsequential or manageable can in fact cascade to consequences that nobody wanted or could imagine. The insight comes from Thucydides in his great history of the Peloponnesian War. He wrote about the competition between the two leading city-states in classical Greece. In probably the most quoted one-liner in international relations study, he wrote, “It was the rise of Athens and the fear that this instilled in Sparta that made the war inevitable.”

You’ve got two variables here: the objective condition of the rise of Power A relative to Power B, and then a subjective condition, which is the perception of that, especially by the ruling power. In the past 500 years, I’ve found there have been 16 cases in which a rising power threatens to displace a ruling power. In 12 of these, the outcome was war. In four, the outcome was not war.

Think about the rise of Germany 100 years ago and the fear that this instilled in Britain. If one asks: How is it conceivable that the assassination of an archduke who would have been successor to the throne in Austria-Hungary becomes the match that lights a fire that, by its end, has burned down all of the European houses? The answer is this occurs in the context of this Thucydidean dynamic. Because it’s fearful of a rising Germany, Britain enters into entanglements which it had rigorously resisted with both Russia and France. And Germany, having only one ally, feels required to back its weakling Austrian-Hungarian empire. Otherwise it would have no allies. So an event that would have otherwise been manageable comes to create a conflagration.

As I argue in the book, at the end of World War I in 1918, what happened to the things that all of the principal actors cared about most? The answer is, they had lost them. The Austrian-Hungarian emperor [“relinquish(ed) every participation in the administration of the State”] and his empire is dissolved. The Russian czar who’s backing the Serbians has been overthrown by the Bolsheviks, so he’s lost his whole regime. The Kaiser in Germany has been dismissed. The French have been bled for a whole generation. And Britain has been shorn of its treasure and its youth and turned into a debtor when before it had been a creditor. So if you’d given a chance to any of these parties for a do-over, nobody would’ve made the decisions that they made. But they were made, and that was the outcome.

So the application to the case of China and the United States today is that no sane person in the U.S. government thinks a war with China is a good idea. Similarly, I don’t believe there’s anybody in China who matters who thinks a war with the U.S. is a good idea. Does that mean war cannot happen? The answer is it does not. But if we look at our histories, we discover that despite the fact that people have the right perception that a war would be catastrophic for their interests, they nonetheless may find themselves making choices in which they are prepared to tolerate risks they normally wouldn’t if they were not caught up in the grips of the dynamics of Thucydides.

Take the Cuban missile crisis and its analogue unfolding today with North Korea. In the missile crisis, Kennedy was prepared to run a 1-in-3 chance of a nuclear war that could kill 100 million people to prevent the Soviet Union from placing nuclear missiles in Cuba. When he got into the middle of this crisis, and especially as he got to the end, he began to have second thoughts. I think as we watch what’s likely to happen over the next year in North Korea, we’re going to see what level of risk of a war Trump will accept to prevent North Korea from being able to launch a nuclear warhead against Los Angeles or San Francisco. I don’t believe it will be less than what Kennedy was prepared to run as a risk. And if you think about it, that’s terrifying.

GAZETTE: You say the U.S. must better understand what China is trying to do. What are they trying to do, and how do we improve our understanding of them? While China is clearly an economic force, there are other dimensions — cultural, political, social, leadership — that comprise what it means to be a superpower.

ALLISON: Absolutely. We should imagine that President Xi and his colleagues are similar to Teddy Roosevelt and his colleagues when the U.S. was supremely confident it was going to be the “American Century.” Teddy Roosevelt, as I describe in the book — a Harvard graduate, one of my heroes, 37 years old — becomes the No. 2 civilian in the Navy. That’s in 1897. He’s been writing that it makes no sense whatsoever to have these foreigners in our hemisphere, especially offended by the Spanish who are controlling Cuba. So in the decade that follows his becoming the assistant secretary of the Navy, we fight a war with Spain, we liberate Cuba, we take Puerto Rico, we get Guam as a spoil of war, and the Philippines. Second, we support and sponsor a coup in Colombia that creates a new country, Panama, that gives us a contract for the canal that we want to build. We threaten war with Britain and then secondly with Germany unless they’ll butt out of territorial disputes in Venezuela, and we ultimately steal the biggest part of the tail of Alaska from Canada, and that’s just for starters.

And we announce, as Teddy does, the Roosevelt Corollary to the Monroe Doctrine. The corollary says if any nation in our hemisphere behaves in ways we don’t like, we will send the Marines and change the government. And we send the Marines once a year every year that follows while he’s there. From the Chinese perspective, what is the name of the sea that’s adjacent to its border? It’s called the South China Sea. It’s not called the American Sea; it’s not called the Asian Sea; it’s not called the International Sea. And this other one is called the East China Sea. When they look out at these waters adjacent to their border, they think it’s as strange and anomalous to see the American Navy as the arbiter of what happens there as Teddy Roosevelt thought it was for the Spanish to be in Cuba.

They aspire to the normal aspirations of a rising power in the Thucydidean story. A rising power thinks “I’m bigger, I’m stronger, so I deserve more say, and I deserve more sway, and my interests deserve to matter more. And the arrangements that I’ve inherited from a previous condition in which I used to be small and weak are unfair and were unreasonable, so they need to be adapted.” When we tell them, “Wait a minute, this is the rules-based international order that’s allowed you to emerge. You would never have emerged if it hadn’t been for what we’ve provided in the way of security and economic order,” that’s what’s under the surface of events happening in the South China Sea and also in the Korea peninsula.

GAZETTE: China is not without its own growing pains. I wonder whether the fact that major economic and cultural changes are hitting China so quickly may hinder its growth and strength. It’s something they’ve never dealt with, so there’s no history to fall back upon. Meanwhile, the U.S. has 240 years of a mostly stable economic and political system, which is a decided structural advantage. Are we perhaps overstating China’s rise much like we did with Japan in the ’80s?

ALLISON: They’re completely shell-shocked by how fantastically their world has changed in such a short period of time. Now of course, our world has changed hugely, too. This book is not pessimistic or fatalistic in any way, but I think it’s essential to recognize the inherent and inescapable risks — extreme risks — in this structural condition.

China has fantastic problems at home, and the U.S. has fantastic problems at home. The Chinese are trying to run six revolutions at the same time. They’ve got their population problem. They’ve got, as you say, no established institutions, so they’ve got no constitutional framework. There are lots of reasons for thinking that they could find themselves in trouble. But of course, that’s been true five years ago, 10 years ago, 15 years ago, 20 years ago. My gut tells me that we should not count on them derailing themselves. We should count on them continuing along this path, and we should expect their behavior to look like what I call the “rising power syndrome.” The emanations from it, I think, give us a pretty good clue to how they think about “one belt, one road,” or what should happen in the South China Sea, or who should be calling the tune with development assistance, particularly as the U.S. exits some of these arenas, putting together a trade agreement in Asia, which I think they will succeed in doing. Or even, as at the Davos discussions, declaring themselves to be the leader in trying to deal with the climate problem. To whatever extent we back off or back down and leave vacuums or empty space, maybe they’ll overstretch and overpromise. But they’re there.

GAZETTE: Despite Thucydides’ Trap, you say war between China and the U.S. is not inevitable. Why?

ALLISON: There’s no reason why it’s necessary to make the mistakes that gave us World War I or that produced a number of the other examples. I try to draw 12 lessons for peace, both from the failures and from the successes. No. 1: Learn from the past. No. 2: Analyze the situation just like you were taking a very high-level strategic perspective. So it is the case that the overwhelming problems for China lie at home. And it is the case that the overwhelming problems for the Americans lie at home. Is it impossible to imagine people having a sense of priorities? No, it’s not. It’s hard, but not impossible. Third, look at the problems that we’re not able to solve unilaterally, that can only be solved if we act cooperatively. Climate is a dramatic example. You can’t solve the problem by yourself. This has to be done either collectively among the big guys, of which China and the U.S. are the two leaders, or it fails. That’s why the Paris Accord was so significant. So there are areas in which cooperation is necessary for our selfish objectives. Climate is a dramatic case, but I think the same thing is in avoiding a nuclear war between the U.S. and China.

Next, for the areas where we have competing interests, can we imagine adjusting things that we’ve become accustomed to, but are not necessary? I call this distinguishing between the vital and the vivid. Can we take account of what’s vital for American well-being and then figure out what other things are maybe important but less important? If we’re to manage the problem that’s emerging in the Korean peninsula, will we have to adjust some of the things that we’ve taken for granted? I think we will. Is compromise a bad idea? In politics, maybe so, but not in the real world and not in strategy.

Diplomacy will be of the essence. This has to do with the way the governments relate to each other, the way the parties understand each other, the level of even trust in the sense of predictable expectations. I think it’s a challenge, but it’s not a challenge all that much more difficult than in the period after World War II and especially in the late ’50s, ’60s, and ’70s when it looked like the Soviet Union was going to surpass the United States. My hope about the book is that we’ll recognize the extreme risks and then we will understand that we need to have a strategic imagination proportionate to the risk.

This interview has been edited for clarity and length.