The race was tightening even before Friday's surprise - the news that the FBI investigation of Mrs Hillary Clinton's classified e-mails was not dead, just resting. According to the RealClearPolitics average of polls, Mrs Clinton's lead over Mr Donald Trump is 5.2 points, down from 7.1 two weeks ago. In the 2015 British general election, pollsters underestimated the Conservative lead by an average of 6.5 points.

This is the Year of the Improbable. Leicester City won the Premier League. Iceland beat England 2-1. It's not over.

Regardless of who wins, however, one thing is certain: the new president will have the opportunity to reshape American foreign policy. Indeed, there is an urgent need for that to happen. Months of electoral muck-raking have had the side effect of leaving the incumbent smelling of roses. As far as foreign policy goes, this is undeserved.

The bombing of Aleppo is only the most extreme illustration of Mr Barack Obama's failure as a statesman. From his anodyne Cairo speech in 2009 until today, he has made a series of misjudgments in the Middle East, the consequences of which - not only in Syria, but also in Iraq and in Libya - have been hideous. The death toll in the Syrian war is somewhere between 300,000 and 470,000. But who knows how much higher it will rise?

The President believed he had an ingenious strategy to establish geopolitical balance between Sunni and Shi'ite. But by treating America's Arab friends with open disdain, while cutting a nuclear deal with Iran that has left Teheran free to wage war and sponsor terrorism across the region, Mr Obama has achieved not peace but a fractal geometry of conflict and a frightening, possibly nuclear, arms race. He has also allowed Russia to become a major (and malign) player in the Middle East for the first time in 40 years.

Meanwhile, little remains of the President's much-vaunted "pivot to Asia". "If you look at how we've operated in the South China Sea," the President boasted to Jeffrey Goldberg in an interview published in April, "we have been able to mobilise most of Asia to isolate China in ways that have surprised China, frankly; and have very much served our interest in strengthening our alliances".



Dr Kissinger's view is that the US should not pursue a policy of containment, much less confrontation, towards China. PHOTO: REUTERS



The Philippines' new president Rodrigo Duterte can't have got this memo. Earlier this month, he went to Beijing's Great Hall of the People to announce his "separation from the United States". So much for America's oldest ally in the Pacific. So much for the "first island chain" bulwark that has been crucial to US strategy in the region since the 1940s. So much for Mr Obama's mantra: "Don't do stupid s**t."

Let us make the assumption that the next president will be Mrs Clinton. What should we expect of her foreign policy? According to her opponent, the answer is nothing less than "World War III", because of the potential for conflict over Syria with Russia, "a country where the nukes work as opposed to other countries that talk".

In the late 1970s, when The Jam were singing about the possibility of an A-bomb in Wardour Street, a Third World War was something we genuinely worried about. Nowadays, it is rather harder to brace ourselves for the end of the world, as opposed to the end of The Great British Bake Off.

Perhaps it was the sight of that Russian aircraft carrier chugging through the English Channel the other day. What was it running on: coal? Or perhaps it's just the fact that America accounts for about two-fifths of all military expenditure in the world. Wars rarely happen when the result is a foregone conclusion.

The conventional wisdom is that Mrs Clinton would be a more hawkish president than Mr Obama. I hope that is true where the Kremlin is concerned. But what about China? In Beijing they indignantly quote her statement that she "doesn't want her grandchildren to live in a world dominated by the Chinese". Yet there is a reason to doubt that, as president, she would automatically play hardball with Beijing. That reason is Dr Henry Kissinger.

In one of the more unlikely exchanges of the Democratic primaries, Senator Bernie Sanders attacked Mrs Clinton for her favourable view of Dr Kissinger. Revealingly, Mrs Clinton's response praised Dr Kissinger's "opening up China and his ongoing relationships with the leaders of China (which) is an incredibly useful relationship for the United States of America".

It was not the first time she had praised Dr Kissinger's China policy. In a rave review of his most recent book, World Order, for The Washington Post, she made clear that his "building a cooperative relationship with China" was her idea of "smart" diplomacy.

A central argument of World Order - also the bottom line of Dr Kissinger's previous book, On China - is that the US should not pursue a policy of containment, much less confrontation, towards China. In his view, such a strategy risks an escalating strategic rivalry between the established power and the rising power - of the sort that throughout history has led to war.

My former colleague Graham Allison calls it the "Thucydides trap", in honour of the ancient Greek historian who first identified the phenomenon, and he estimates that rival powers have fallen into it many times over the centuries.

For Dr Kissinger the most troubling analogy is Britain and Germany before 1914. Back then, Britain was the incumbent and Germany the challenger. Today, President Xi Jinping is sitting roughly where Kaiser Wilhelm II did. Mrs Clinton does not want to be Herbert Asquith, who ended up taking Britain to war with Germany.

How can America and China steer clear of the Thucydides trap? According to Dr Kissinger, only by adopting a policy that he calls "co-evolution". Rather than attempting "to organise Asia on the basis of containing China or creating a bloc of democratic states for an ideological crusade", Washington would do better to work in partnership with China to build a new "Pacific community".

It is an argument eloquently restated by his protege Joshua Ramo in a brilliant new book, The Seventh Sense. To my mind it implies a return to the geopolitical geometry of the 1970s, when America used its new relationship with China to put the Soviet Union on the back foot.

If Mrs Clinton becomes president, she will face a choice: to continue with the failed policies of the Obama administration, in which she served as secretary of state, or to become Hillary Clissinger.

Doing so would mean dropping the China-bashing rhetoric she has sometimes indulged in. But why not? Her husband did precisely that when he was president.

During one of his 1992 debates with Mr George H. W. Bush, Mr Clinton accused Mr Bush of "coddling" dictators, notably "the butchers of Beijing". Yet when he was seeking re-election, a scandal erupted over murky donations to the Democratic national committee by people who, Republicans alleged, were Chinese agents. Amid the usual pomp and ceremony, the Clintons visited China in June and July 1998.

Murk notwithstanding, I would much rather see Mrs Clinton back in Beijing than Mr Trump in Moscow, glad-handing the Butcher of Aleppo.

THE SUNDAY TIMES, LONDON