The Next Great War


Graham Allison is the former director of Harvard’s Belfer Center for Science and International Affairs and the Douglas Dillon professor of government at Harvard Kennedy School.

On Sunday, the world will pause to remember the 100th anniversary of the final day of a war so devastating that it required historians to devise an entirely new classification for it: “world war.” On the 11th hour of the 11th day of the 11th month in 1918, the guns of World War I fell silent — and nearly 20 million people lay dead.

Could such a conflict happen today? After more than seven decades without a shooting war between great powers, many Americans find the thought of the United States and a major adversary like China killing millions of one another’s citizens virtually inconceivable.

But when we say something is “inconceivable,” we should remember this: the realm of what is possible is not bound by what our limited minds can conceive. In 1918, in a scene described in Barbara Tuchman’s gem, The Guns of August, then German chancellor Theobald von Bethmann-Hollweg famously responded to a colleague who demanded to know how the war could have happened: “Ah, if only we knew.”

The deeper structural cause of World War I follows a familiar historical pattern: a rapidly rising power, Germany, challenging the primacy of an established one, Great Britain, which had ruled the world for a century. The Athenian historian, Thucydides, famously captured this pattern in his analysis of the war that devastated the two major city-states of classical Greece: “It was the rise of Athens and the fear that this instilled in Sparta that made war inevitable.” In the past 500 years, the world has seen 16 cases in which a rising power threatened to displace a ruling power. Twelve ended in war; only four did not.

In this dangerous dynamic — the Thucydides’s Trap — both rivals become extremely vulnerable to third-party provocations, or even accidents, that trigger a cascade of reactions, at the end of which they find themselves in a war neither wanted. In classical Greece, the detonator was a conflict between a quarrelsome ally of Sparta and a city-state seeking to align with Athens. In 1914, it was the assassination of a minor official, Archduke Franz Ferdinand of Austria. His killing in June appeared so inconsequential to leaders in Great Britain and Germany that none of them bothered to cut short their vacations. Nonetheless, just five weeks later, this spark had produced a conflagration that in the end left all the great nations of Europe devastated.

Today, the intensifying rivalry between a rising China and a ruling United States could lead to a war that neither side wants and that both know would be even more catastrophic than World War I. But it is a familiar contest, for which we can look to history for some lessons. None of the national security leaders in either country has any direct experience in handling a hot war between two superpowers. They must, therefore, study statesmen who have faced analogous challenges.

In the summer of 1962, just months before the Cuban Missile Crisis, John F. Kennedy, who had fortunately read Tuchman’s book, found himself haunted by Bethmann-Hollweg’s words. And so, in managing the most dangerous nuclear crisis the world has ever seen, he explicitly applied lessons from what statesmen had done, and failed to do, in World War I.

What are those lessons for today’s leaders in Beijing and Washington? Three top the list: realistic recognition of risks inherent in the current Thucydidean rivalry, collaborative initiatives to defuse or prevent the most dangerous potential crises and preparation to manage crises that nonetheless occur.

To maximize the chances of adding the U.S.-China rivalry to the short list of averted wars, joint crisis prevention initiatives should focus on the scenarios most likely to trigger unwanted escalation. Current cooperation between the United States and China against North Korea’s nuclear advances is encouraging. But should this effort fail — as most experts are betting it will — and North Korea resumes testing intercontinental ballistic missiles and nuclear warheads that could strike the American homeland, this picture could quickly darken. President Trump might then feel compelled to attack North Korea to prevent it from acquiring such capability. And if the United States attacks North Korea, most experts expect a second Korean War — pitting, as it did in the first, Americans against the Chinese.

Taiwan is another flashpoint. For China, Taiwan is a “core interest” — regarded as much a part of China as Alaska is to the United States. Any attempt by Taiwan to become an independent country could easily become a casus belli. In 1996, when the Taiwanese government took initial steps toward independence, China conducted extensive missile tests bracketing the island to coerce it to stop. The Clinton administration moved two U.S. carriers into the area, forcing China to back down. Ever since, China has been building up specific military capabilities — such as anti-carrier missiles — to ensure it need never concede again. If a single U.S. carrier were sunk in a similar showdown today, the deaths of 5,000 Americans could set the United States and China on an escalatory ladder that has no apparent stopping point.

Preparation to manage these potential crises requires an entire toolbox of precautions. These begin with identifying possible crises, tabletop exercises exploring responses, the creation of circuit breakers that prevent automatic escalation and, most importantly, robust channels of communication. In current U.S.-Chinese relations, this includes not simply regular communication between the two presidents, but also the more recently established hotline between the two ministries of defense and communication at lower levels of command.

But will these preventive and mitigating steps suffice to allow the United States and China to escape Thucydides’s Trap? I doubt it. Unless President Xi Jinping fails in his aim to “make China great again,” China will continue to challenge, and in many arenas, displace the United States from its accustomed position at the top of the global pecking order.

What we need is nothing less than a new strategic concept that redefines the essence of this relationship. For inspiration and clues, we should consider the way J.F.K. reframed the U.S. rivalry with the Soviet Union. In his celebrated commencement address at American University just months before he was assassinated, he proposed moving beyond unlimited Cold War to build a “world safe for diversity.” Without wavering in his conviction that a U.S.-led free world was superior to the Communist empire, he suggested nonetheless that the United States could find a way to live with a deadly adversary that championed values he abhorred.

Could the United States and China find their way to a dynamic in which they compete peacefully? Could we invent a new concept that combines ruthless competition in some arenas with deep cooperation in others? Remembrance of the senseless destruction that came to an end 100 years ago should spur a surge of strategic imagination in addressing this century’s cardinal challenge.

This was produced by The WorldPost, a partnership of the Berggruen Institute and The Washington Post.

Correction: This op-ed has been updated. The original had mislabeled Thucydides as the “father and founder of history.”