It was not immediately clear whether Trump's telephone call with Tsai Ing-wen marked a deliberate pivot away from Washington's official "One China" stance, but it fuelled fears he is improvising on global affairs.
When President-elect Donald Trump spoke to Taiwanese President Tsai Ing-wen on Friday, he not only broke decades of US protocol, he also opened the door to potential trouble with China - which has long refused to recognize the controversial island as a separate nation.
After the phone conversation, Trump tweeted that Tsai "CALLED ME".
Speaking earlier, hours after Friday's telephone call, Chinese foreign minister Wang Yi pointedly blamed Taiwan for the exchange, rather than Mr Trump. You are doing wonderful work which is visible in every way.
By accident or by design, Trump seems to be the first US leader to formally communicate with the Taiwanese president in over 30 years.
Washington remains Taiwan's most important political ally and sole arms supplier, despite the lack of formal diplomatic ties, the irony of which was not lost on Trump.
Since then the USA has adhered to the "one China" principle, which officially considers the independently governed island to be part of the same Chinese nation as the mainland.
The U.S. sold arms to Taiwan as recently as previous year.
On Friday, Trump and Tsai spoke over the phone during which the two leaders noted the "close economic, political, and security ties" between the US and Taiwan.
Not since Jimmy Carter was in office has a president-elect or president taken a call with Taiwan's leadership.
While the USA does not recognize Taiwan as an independent nation, it sold the island $12 billion worth of arms in the 1970s as part of an agreement that commits Washington to helping Taiwan defend itself.
A statement from Trump's transition team said he spoke with Tsai, who offered her congratulations.
The President-elect followed that tweet up with another, in a response to critics: "Interesting how the USA sells Taiwan billions of dollars of military equipment, but I should not accept a congratulatory call".
"I've lived with this policy area my entire adult life and I've lived with the arguments around this for more than 25 years".
The 10-minute phone conversation between Tsai and Trump Friday night Taiwan time was unprecedented since Washington switched recognition from Taipei to Beijing in 1979.
The call with Trump could "convince people in Taiwan that the island can establish good relations with the US and encourage (Tsai) to continue to resist pressure from Beijing", Shi said.
"We ought to have the larger strategic interests in mind", Ng said. "Those are goals of the government and there's no conflict among the goals". Vox accused Trump of "throwing decades of US-China policy in disarray".
Trump has yet to name a secretary of state.
The statement somewhat avoided blaming Trump, who has no previous political, yet alone foreign policy experience.
President Barack Obama's White House said the outgoing U.S. administration had not changed its stance.
Trump's national security spokesman Ned Price said: "We remain firmly committed to our "one China" policy".
Shortly after Trump won the elections, Chinese netizens initially responded with humor and praise. The Chinese Embassy in Washington declined to comment.
But for some critics, in extending his hand to Taiwan, Trump crossed a risky line. Just read what China's Foreign Ministry has to say about the situation, which our president-elect does not seem like he's taking seriously.