“The growth in the power of Athens, and the alarm which this inspired in Sparta made war inevitable.” This is the most famous line of Thucydides’s “History of the Peloponnesian War”. Will a future historian one day write that the growth in the power of China, and the alarm which this inspired in America, made war equally inevitable? 

Since the election of Donald Trump, the probability of a Sino-American conflict has soared. Last year Trump ran an aggressively anti-Chinese election campaign, repeatedly threatening to impose tariffs on Chinese imports. Trade is only one of several bones of contention. The United States remains committed to freedom of navigation in the South China Sea. China’s island-building program is designed to make that sea Chinese in fact as well as name. Trump is less committed than any US president since Richard Nixon to the “One China” policy. 

But the biggest flashpoint is without question North Korea — which brings me back to Thucydides and Graham Allison’s “Destined for War,” this summer’s must-read book in both Washington and Beijing. 

Small powers can cause big trouble. The initial clash in the Peloponnesian War was in fact between Athens and Corinth; war came when the Corinthians appealed to the Spartans for help. Think of the role Serbia played in the First World War, or Cuba in the Cold War. Today’s catalyst for conflict is North Korea, which last week successfully launched its first intercontinental ballistic missile — a weapon with the capacity to hit Alaska. Experts such as my Stanford colleague Sig Hecker believe the North Koreans are just five or so years away from being able to build a nuclear warhead small enough to fit on the nose of such a missile. 

Trump says he won’t tolerate that. On June 30 he tweeted: “The era of strategic patience with the North Korea regime has failed. That patience is over.” But what exactly to do? In essence, he has four options, three of which have already failed. ...