By once again testing China’s nerves over Taiwan, Donald Trump is injecting a dangerous element of uncertainty and unpredictability into US relations with Beijing – the exact opposite of what American presidents usually try to do when dealing with potentially hostile rival superpowers.

Trump’s public questioning of the long-established One China policy, under which Washington accepts that Taiwan is part of China, is a knife in the troubled heart of the US-China relationship established by Richard Nixon’s famous “opening to China” and his groundbreaking meeting with Mao Zedong in 1972.

At the same time as riling China, Trump is fomenting a triangular strategic upheaval by building bridges to Russia. His expected choice of Vladimir Putin’s buddy and Exxon Mobil oilman Rex Tillerson as secretary of state is the latest straw in the wind. In effect, Trump is playing Nixon’s “China card” in reverse. His approach can be summed up: make nice with Russia, talk tough to China.

Trump’s willingness to upset the global balance of power and roll the strategic dice so dramatically heralds a new age of uncertainty in international relations. It potentially affects ongoing crises and looming controversies from Syria and Ukraine to Tibet and the Arctic, where US and Russian oil companies have shared interests.

The symbolic importance to China’s communist leaders of reunification with Taiwan – the last bastion of Chiang Kai-shek’s nationalists in the civil war that followed Japan’s defeat in 1945 – cannot be overestimated. They regard Taiwan as a renegade province and its sovereignty as non-negotiable.

Trump’s statement on Sunday linking continued US adherence to the One China policy to other problematic issues, such as trade and currency, will be deeply alarming for Beijing.

In its toughest riposte to date, Geng Shuang, foreign ministry spokesman, said “the sound and steady growth of China-US relations [was] out of the question” were Trump to persist with his approach. “We urge the incoming US administration … to properly deal with Taiwan-related matters in a prudent manner,” Geng said.

Trump and prudence are not traditional bedfellows. Far from soothing Beijing’s fears following his protocol-shredding telephone call with Taiwan’s president, he deliberately escalated the row. Maybe Trump was trying to justify his earlier gaffe; maybe his sense of self-importance was punctured. Nobody could tell him who he may and may not speak to, he said.

Or maybe Trump was placing China on notice that unless he obtained more balanced trade and jobs, the US would deem all aspects of the bilateral relationship – including regional security, China’s military buildup and cooperation over the threat posed by North Korea’s nuclear weapons programme – up for review.

“We’re being hurt very badly by China with devaluation, with taxing us heavy at the borders when we don’t tax them, with building a massive fortress in the middle of the South China Sea, which they shouldn’t be doing, and frankly with not helping us at all with North Korea,” Trump said. “You have North Korea, you have nuclear weapons, and China could solve that problem and they’re not helping us at all.”

Chinese leaders – from the president, Xi Jinping, down – have not yet decided how to deal with Trump. His post-election outbursts have evidently caught them off-guard. State media and tame pro-government academics are increasingly aggressive in their response. But party bosses still seem to be hoping things will calm down as Trump settles into office.

That may be a serious misreading. Trump is already engaged in a furious battle with his own intelligence community, notably the CIA, and moderate Republican and Democratic members of Congress. There is little reason to believe he will tread more gently with with his favourite campaign target, China – at least in the short term.

But there could also be method in the apparent madness. By seeking warmer ties with Russia, Trump may be hoping China catches a cold. This is the identical gambit, played backwards, that was employed by Nixon and Henry Kissinger, his national security adviser, to clip the wings of the Soviet Union at the height of the cold war. On this reading, Trump is playing the “Russia card” against Beijing.

The risks that this strategy will backfire are huge. Xi is not the sort of leader to appease Trump; China has its own pragmatic, business-like relationship with Putin’s Russia; the two countries will not be easily estranged. And in any case, China does not accept the justice of Trump’s claims about currency manipulation and unfair tariffs. And then there is Taiwan.

Xi may decide instead to meet fire with fire. Threatening Chinese military air manoeuvres close to Taiwan and the Ryukyu islands at the weekend – the second such event in two weeks – led to a rapid mobilisation of Taiwanese and Japanese air and missile forces. A connection between this and Trump’s verbal provocations is not proven. But it seems likely. In the coming age of uncertainty, nobody knows what comes next.