Image copyright Getty Images Image caption The US clashed with China earlier this year over steel imports

Donald Trump's surprise election victory has caused widespread jitters throughout Asia, echoing global concern over the implications of a more isolationist and protectionist attitude by the US during his time in office.

Mr Trump's approach to the world's most important bilateral relationship - China and the US - is still a relative unknown, fuelling speculation over whether the US will eventually recede from the Asia-Pacific region and allow China to fill the vacuum.

Some conservatives in China have suggested that the US must finally face the reality of China overtaking the US as the leading regional power. The reality of Mr Trump's approach, however, may be "congagement": a mixture of enhanced containment and engagement, as opposed to the "smart power" doctrine of the Obama years.

During his presidential campaign, Mr Trump suggested that US allies in the Asia Pacific, such as Japan and South Korea, must do more to secure their neighbourhood and must shoulder more of the cost of the US alliance network.

An early indication of his approach may emerge when he meets Japanese Prime Minister Shinzo Abe for the first time on Thursday next week. Sources close to Mr Trump have suggested that encouraging Mr Abe's goals of a more muscular military response towards China would help share the burden among the alliance.

This has been interpreted with alarm in both Beijing and Tokyo. But one of Mr Trump's strategic advisers, former CIA director James Woolsey, has recently suggested a "grand bargain" with China: Washington's acceptance of China's stake in the region in exchange for Beijing's acceptance of the regional status quo.

Image copyright Getty Images Image caption Mr Trump has made no secret of his objection to the Trans Pacific Partnership deal

Another clue to Mr Trump's approach may lie in a letter written to Congress in May 2015 by 25 former cabinet secretaries, including seven former secretaries of defence and 10 former treasury secretaries from both Republican and Democratic administrations.

In the letter they called for Trade Promotion Authority legislation to be enacted, making the link between strengthening existing and emerging security relationships in the Asia-Pacific region and reassuring the region of America's "long-term staying power".

They went on to stress that the Trans Pacific Partnership (TPP), the Obama administration's blueprint for free trade with the US across the Asia-Pacific region, would shape an economic dynamic over the next several decades by linking the US to one of the world's most vibrant regions.

They also warned that allies and partners would question US commitments, doubt American resolve, and inevitably look to other partners. They stressed that America's prestige, influence, and leadership was on the line.

Those who signed the letter may now be alarmed to see some of their fears playing out. Philippine President Rodrigo Duterte has announced his country's "separation" from the US, and Malaysia too may have been attracted into China's embrace in the wake of Prime Minister Najib Razak's state visit to China last week, where new defence and investment deals were signed.

Image copyright Getty Images Image caption Mr Trump's victory has caused widespread jitters throughout Asia

Most observers now view the TPP as dead in the water. Hillary Clinton disavowed herself of the deal during her campaign, in an attempt to appease concerns within the US business community, and the TPP has struggled to gain traction during exhaustive negotiations even with the staunchest of US allies such as Japan.

Nevertheless, the end of the TPP should not be viewed as the death knell of US economic engagement in the Asia Pacific. For its part, Beijing is deeply concerned over "de-globalisation", part of a global trend of economic retrenchment. China over the past decade has been a major proponent of free trade, working hard to strike deals bilaterally and in multilateral bodies, fuelling its meteoric growth in terms of political, economic and military clout.

The pinnacle of this growth occurred during the second Obama administration, prompting China's President Xi Jinping to proclaim a "new model of great power relations" during his first state visit to the US.

The China-US relationship during this period came to be defined as both co-operative and competitive. Mr Xi has frequently stated that the common interests of the US and China far outweigh their differences.

Despite growing strategic mistrust, economic interdependency became the cornerstone of the US-China relationship, demonstrated by the success of the recent G20 meeting in Hangzhou towards the end of Mr Obama's term.

Image copyright Reuters Image caption China's island-building in the South China Sea has raised the hackles of neighbours and the US

If Mr Trump were to undermine this stability and interdependency by imposing new trade strictures, threatening China's economic "new normal", this could have severe consequences for China's economic reform agenda and the legitimacy of the regime.

These are all deeply divisive issues within the Chinese Communist Party and will feature prominently at the next leadership conclave, the 19th Party Congress in one year's time.

In all likelihood, Mr Trump will understand that neglecting US pre-eminence in the Asia-Pacific region will have deep economic consequences for the US and may corrode the US alliance network that has served as the bulwark for regional security since the end of World War Two.

He will also be aware of deep bipartisan resentment over the Obama administration's inability to curtail assertive Chinese behaviour in the South China Sea, including the construction of three new air and naval bases on disputed atolls.

Rather than exacerbating the relative decline of US power in the region, Mr Trump in fact may seek to push back against any new Chinese coercion in its neighbourhood, while engaging with China more stridently on Beijing's big-ticket, geo-economic plans, such as the Belt and Road initiative and the Asian Infrastructure Investment Bank (AIIB).