Donald Trump’s tweaking of Chinese noses is growing more provocative following Beijing’s criticism of his controversial phone conversation last week with Taiwan’s normally off-limits leader. The US president-elect’s latest intervention, conveyed via Twitter rather than diplomatic channels, includes complaints about China’s regional military buildup and alleged currency manipulation.

China’s official reaction has so far been restrained, but teeth are being firmly gritted in Beijing. Like the rest of the world, Xi Jinping’s government has not yet decided whether Trump is being deliberately confrontational or is simply out of his depth. Beijing initially blamed the Taiwanese for “tricking” Trump into talking to President Tsai Ing-wen – the first acknowledged contact at this level for nearly 40 years. But it has emerged that Tsai kept quiet about the call, expecting it to remain private (as has been usual in the past). It was Trump who bragged about it in public, embarrassing the Chinese.

His latest tweets were both infuriating and alarming for Beijing.

Did China ask us if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into.. — Donald J. Trump (@realDonaldTrump) December 4, 2016

their country (the U.S. doesn't tax them) or to build a massive military complex in the middle of the South China Sea? I don't think so! — Donald J. Trump (@realDonaldTrump) December 4, 2016

During the election campaign Trump criticised China’s trade practices as unfair and, like the Obama administration, objected to island-building in disputed areas of the South China Sea deemed illegal by a UN court ruling. But he has also, at times, adopted a more conciliatory, realpolitik stance.

Puzzling over this Jekyll and Hyde act, China is hoping Trump the pragmatic deal-maker will eclipse Trump the hostile rabble-rouser. “For us, for China, we do not comment on his personality. We focus on his policies, especially his policies toward China,” Lu Kang, foreign ministry spokesman, said on Monday. China wanted a “sound and stable relationship [that] accords with the joint interests of both peoples”.

Despite his emollient words, Lu reminded the Trump camp that China regarded Taiwan, whose defence and de facto independence from China is effectively underwritten by Washington, as the most important and sensitive bilateral issue with the US. Beijing describes reunification with its “breakaway province” as a core interest. Xi has warned that the current status quo cannot continue indefinitely.

Nor has it gone unnoticed in Beijing that Mike Pence, the US vice-president-elect, declined opportunities at the weekend to reaffirm the traditional “One China” policy that has frozen differences over Taiwan for decades. Military contingency plans are doubtless being dusted off in Beijing.

Reaction in Taiwan to Trump’s rushing in where diplomatic angels fear to tread has been both febrile and fearful. Supporters of independence, including some within Tsai’s ruling party, are talking about a “new model” of closer relations with the US, extending beyond trade and defence to cooperation on the international stage.

Reports are circulating in Taipei that Tsai may meet Trump in person next month during a stopover in New York, en route to Nicaragua, one of Taiwan’s few allies. Such a meeting would be sensational – and is likely to provoke an open rift with Beijing. Tsai’s spokespeople described the reports as “wild speculation” but did not specifically deny them.

Meanwhile, opposition MPs from the Beijing-friendly Chinese Nationalist party (KMT) and political commentators warned that Trump’s meddling could create a cross-straits crisis of the kind last seen in the 1990s, when Bill Clinton sent warships to defend Taiwan amid a menacing Chinese missile buildup.

Xi is already ill-disposed to the Tsai government and has suspended talks and other exchanges. Tsai’s domestic critics say Taiwan could pay a high price for Trump’s blundering. They point to an editorial in the Global Times, a Chinese government mouthpiece, headlined “Talk to Trump, punish Tsai administration”.

Trump’s Taiwan trial balloon has put the wind up the entire region, where tensions linked to China’s growing economic dominance, military buildup and territorial ambitions are ever-present. Several Asian allies contacted Obama’s White House at the weekend to ask what was going on. But Obama is probably as much in the dark as everybody else.

In response to an offer by John Kerry, the secretary of state, to coach Trump on delicate international issues such as Taiwan, Kellyanne Conway, a senior aide, noted memorably that the president-elect was “not a talking points kind of guy”.

