McGregor describes China and Japan as “global powers, with the world’s second- and third-largest economies, backed by robust, advanced militaries”. Completing the triangle is the United States, the world’s largest economy and the traditional guardian of “Pax Americana” in Asia.

But the situation has been destabilised by the election of Donald Trump as US president and recent threats from North Korea. It is in this context that Asia’s Reckoning looks at the political, business and military ties between China, Japan and the US, from the post-war era to today.

McGregor is an author and journalist by trade, not a policy wonk, so Asia’s Reckoning is filled with colourful anecdotes and behind-the-scenes intrigue.

There are great descriptions of Chinese and American leaders putting on acts for each other. McGregor describes Deng Xiaoping as a “diminutive, Mao-suited vice-premier” who “donned an oversized cowboy hat at a Texas rodeo” in 1979. McGregor talks about the time Jiang Zemin recited Abraham Lincoln’s Gettysburg address for Bill Clinton as a “party trick” in the 1990s.

In 2013, then US president Barack Obama invited Chinese President Xi Jinping for a private dinner at a California resort, and a casual stroll through the Sunnylands estate. The idea was to get Xi out of his usual meetings in Washington and Beijing, and past his pre-scripted speeches.

According to transcripts, Xi kept up his polite but stony-faced manner, and only became agitated when Japan was discussed. “The US president raised his hands over his head like a stop sign, as if he were a schoolteacher,” McGregor writes.

Diplomacy is often driven by individual personalities, not just politics, and these details add much interest to the book. Asia’s Reckoning starts with Japan climbing out of the shame and destruction of the second world war, when it had been attacked with nuclear weapons and stripped of its military. With its defence matters firmly in US hands, Japan was looking ahead and putting a laser focus on its economy.

By the late 1970s and 1980s, Japan was flooding the world with cars, television sets and other electronics. Its steel mills were putting the US rust belt out of business, and its factory production lines were among the first to use robots.

Most Americans were aware that all the VCRs in their stores came from Japan. But less well known (or perhaps just conveniently forgotten today) was the fact that Japanese loans underwrote the early years of Chinese manufacturing, which would later take off in a way that nobody could predict.

In the ’70s, impoverished communist China was just beginning to open up to the West, with talks with US President Richard Nixon and Secretary of State Henry Kissinger (who was said to have been enamoured with “sophisticated philosopher kings” Mao Zedong and Zhou Enlai).

At the same time, Japan was not exactly coy about its econo­mic success. A commentator in the respected Asahi Shimbun newspaper wrote in 1980 that “watching the United States suddenly lose its magnificence is like watching a former lover’s beauty wither away. It makes me want to avert my eyes”.

But by the ’90s, Japan’s economic dominance in Asia had ended. “How do we know that you won’t abandon us for China?” Japanese politician Koichi Kato asked fretfully of the US at that time. “They are the new girl, we are the old mistress.”

In one generation, the tables had turned between the two.

Historical Sino-Japanese tensions often in the news today were barely mentioned in the post-war period, although horrors would have been much fresher in people’s memories.

There was, in some sense, more openness in the past.

From 1952 to 1959, the Nanking massacre was not mention­ed once in the People’s Daily. In 1978, Deng conducted a no-holds-barred press conference, something rarely done in Beijing today. He casually brushed aside queries about the disputed Diaoyu/Senkaku Islands in the East China Sea, which are now a hot-button topic.

Even diplomacy between the two sides seemed softer. “You cannot be asked to apologise every day, can you?” Mao allegedly told a Japanese delegation. Meanwhile, Zhou assured Tokyo their conflicts were “in the past, and we should let go of the history and ensure [it] is never repeated”.

So what happened? McGregor is not the first expert to note that, as China and South Korea became richer and more power­ful, they found these histories to be politically useful in stirring up nationalism.

And China’s dominance – from global investments, to internet control, to a modernising military – make Japan’s earlier strength in areas such as camcorders seem little more than a historical footnote.

Covering 350 pages, Asia’s Reckoning continues in this vein through the Bush, Clinton and Obama years.

It also includes an afterword addressing the first few months of Trump’s presidency. This is fast work for a major book release in September, but it is still not fast enough, given how much shocking news comes out of the Trump administration almost daily.

Foreign policy analysis normally relies on some common assumptions: that the US wants Asian allies, will abide by legal treaties, will stick to core policies such as free trade, and has a president with basic knowledge of the outside world.

Those assumptions have been thrown out the window. Nobody even knows who will be on the White House staff in a few months, much less what Washington’s take will be on complex China-Japan relations.

One of McGregor’s arguments is that Sino-Japanese tensions, which are playing out in various disputes across the region, may cause more global damage than most people expect.

Another is that the US can no longer see itself as the guardian of East Asian peace and diplomacy. For better or worse, Asian nations are confidently dealing directly between themselves.

Asia’s Reckoning is not a crystal ball. It isn’t going to predict whether North Korea will attack America, or if America will stand up for Japan or Taiwan if China attacks, or if anyone will attack anyone else in East Asia at all.

But it is an excellent modern history book that explains the roots of the complex political, business and military ties between major superpowers. In an age of rocky global politics, Asia’s Reckoning provides the context needed to make sense of the region’s present and future.

“Any clash between China and Japan would not be a simple spat between neighbourhoods,” McGregor writes. “A single shot fired in anger could trigger a global economic tsunami, engulfing political capitals, trade routes, manufacturing centres and retail outlets on every continent.”

That comment might be a tad dramatic. Still, the first world war was triggered by the shooting of a single archduke. Why couldn’t a maritime spat – or even an unwise tweet – do the same in 2017?