The reasons for this moderation have been complex and varied. One leading explanation is the view that China's economic growth poses no problem for the US, because rising global wealth is not a zero-sum game. China-US trade was mostly seen in classically liberal, free-trade terms: It made everybody better off by offering low-priced goods to American consumers and jobs for Chinese.
But the main reason for moderation is surely that both President George W. Bush and President Barack Obama judged that there wasn't much they could do about China's rise and the enhanced negotiating power that comes with it - especially while China remains the single largest non-US holder of Treasury debt.
Militarily, both Bush and Obama maintained the traditional hub-and-spokes security relationship with various Pacific nations, in effect containing China without using that provocative word.
Trump sees things very differently. He depicts China's growth as illegitimate, caused by unfair currency policy rather than the export of goods at rock-bottom prices. He is already demonstrating that he believes he can change the negotiating calculus by revisiting the traditionally accommodating US position.
Meanwhile, Trump seems fairly unconcerned about China's regional geopolitical ambitions. On the campaign trail, he criticized the US treaty obligation to defend Japan and called on Japan to pay more for US troops stationed there.
That's a 180-degree turn from the recent US approach. Bush and Obama basically welcomed China's economic growth, but were wary of the nation's increasing military strength. Trump seems suspicious of China's economic progress but unworried about its geopolitical influence.
How China will respond depends very much on Xi Jinping's perception of his nation's economic and strategic interests - and his own political objectives. China's export-driven economy cannot afford a trade war with the US
Holding vast amounts of US debt is a form of leverage, to be sure; but it also means China can't afford to push the US into a position where its bonds fall sharply in value. Trump's history of bankruptcy is an extra reason for Chinese caution on this front.
At the same time, Xi has committed himself, and the Chinese Communist Party, to a nationalist domestic strategy. Given the inevitable decline of economic growth in China from its world-historical heights, only nationalism promises to shore up the party's legitimacy.
The nationalist imperative will matter especially to Xi if he decides to try to stay in power longer than 10 years, thus breaking the norm developed by two decade-long cycles of Chinese politics. If he does, he will need a still stronger nationalist rationale to justify the deviation.
Given all this, it's reasonable to expect Xi to show strength against Trump through symbolic military aggressions - like the anti-aircraft batteries in the Spratly Islands and the underwater drone stunt. That plays better with the Chinese domestic audience than economic responses.
If that happens, Trump will have to reconsider the question of China's military stance. He could reply with cheap talk. Or he could adopt something like the Obama approach - putting US F-22 fighter jets in Australia.
The danger of military escalation is not small. The danger of economic escalation isn't either. For all the talk about Vladimir Putin and Russia, Trump's presidency may well come to be defined by his relations with China.
