Donald Trump’s exchange with Taiwan’s leader broke with nearly four decades of the ‘one China’ policy.

J Berkshire Miller is the director of the Council on International Policy.

Last week, the US President-elect Donald Trump accepted a phone call from Taiwan’s President Tsai Ing-wen and discussed common economic and security interests with Taipei. The phone call also offered Tsai an opportunity to congratulate Trump on his surprising election victory last month over Democratic favourite Hillary Clinton.

Normally such a call would be benign, but due to the delicate role Taiwan plays in relations between China and the United States, the call has raised alarm bells on the clarity and caution by which Trump will conduct his relations with the world’s second biggest economy.

Having a direct exchange with the Taiwanese leader broke with the “one-China” policy to which the US has adhered for nearly four decades. Acceptance of this policy over the years has been bipartisan and not breached even during the low points in Washington’s ties with Beijing.

China regards Taiwan as part of its inherent territory and has always been tough on attempts by either Taipei or the international community to legitimatise its status as independent.

Washington’s relationship with Taipei is most sensitive due to its security guarantees and support for Taiwan – enshrined in the 1979 Taiwan Relations Act.

Beijing has responded to Trump’s move with concern but also caution, with Foreign Minister Wang Yi directing the blame towards Taiwan by describing the phone call as a “petty trick” by Tsai.

Beijing also directed “solemn representations” to US diplomatic officials – a reminder of Taiwan’s integral part of the grand bargain of the “one-China policy”, and US-China relations more broadly.

Trump has looked to shift the attention towards Taipei – stressing that the exchange originated from Taiwan. This is a dangerous move as it provides an opening and justification for Beijing to turn the screws harder on the Tsai government.

Shaking-up the old policies

Cross-strait ties were already floundering after Tsai’s election back in January, through which her Democratic Progressive Party, with a large pro-independence support base, was catapulted into power, curbing decades of political control by the nationalist Kuomintang party.

Tsai’s ability to secure an exchange with the next US president is thus a blessing and a curse, as it draws Washington closer on the one hand but opens the gates to more potential conflict with the Chinese mainland.

In typical Trump fashion, the president-elect is unapologetic and resents criticism from Beijing and the US foreign policy elite.

Trump was less vociferous during the pre-election period on China's destabilising activities in East Asia, causing consternation among most of Beijing's neighbours.

Indeed, Trump publicly lambasted Beijing for daring to criticise his conversation with Taipei: “Did China ask us [the US] if it was OK to devalue their currency (making it hard for our companies to compete), heavily tax our products going into their country (the US doesn’t tax them) or build a massive military complex in the middle of the South China Sea? I don’t think so!”

Why would Trump look to break away from decades of established US policy? The approach to Taiwan is an example that further clouds how Trump might govern US interests in Asia.

OPINION: The new Taiwan crisis

Indeed, he and his advisers may be looking to “shake up” China policy and derail the attitude Beijing has adopted, especially over the past eight years, that it can essentially have carte-blanche on regional security matters with little real interference from Washington.

That said, it is important not to overstate any shifts. Trump’s exchange with Tsai may be an example of diplomatic naivety and his “shoot-from-the-hip” style, rather than any calculated plan to upend decades of US-China policy.

Indeed, this is not the first puzzling diplomatic gaffe Trump has made since being elected – as demonstrated by his bizarre phone call with Pakistan’s Prime Minister Nawaz Sharif. However, words matter in international affairs and Trump – and his successors – will have to carry this incident, and it consequences, into his administration.

China wants predictability

Shortly after Trump’s surprise election last month, China was scrambling to understand how the new administration would orient its foreign policy and, most importantly, how it would approach US-China relations.

Trump, the campaigner, frequently castigated Beijing for its unfair trade practices and promised to tighten the vice by labelling it a currency manipulator and imposing tariffs of Chinese imports.

On the other hand, Trump was less vociferous during the pre-election period about China’s destabilising activities – especially in the maritime domain – in East Asia, causing consternation among most of Beijing’s neighbours.

REPORTER’S NOTEBOOK: Trump’s Taiwan call opens questions about his Asia agenda

Moreover, Beijing was no fan of Hillary Clinton and appeared to celebrate her stunning defeat with high hopes for Trump’s unique brand of fusing populism at home with isolationist tendencies abroad.

China also eagerly watched the election campaign as Trump slammed the importance of long-standing US alliances with Asian allies – including Japan and South Korea – and described the Trans-Pacific Partnership trade pact, a key plank of Obama’s Asia policy, as a “disaster”.

This mini-honeymoon has now come to an abrupt halt and China is realising that sometimes predictability, even if you don’t like its trappings, is easier to navigate in its relations with Washington.

J Berkshire Miller is the director of the Council on International Policy and is a fellow on East Asia for the EastWest Institute.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial policy.