Taiwanese President Ma Ying-jeou, left, shakes hands with Chinese President Xi Jinping before their historic meeting in Singapore in November. (Roslan Rahman/AFP via Getty Images)

With the opening of a hotline came the drawing of a red line.

On Wednesday, China announced that a new dedicated phone link had been inaugurated with Taiwan in an effort to build trust between the longtime rivals and maintain the peace across the narrow strait that divides them.

But at the same time, Beijing warned the island, which it still considers a renegade province, that rough seas could lie ahead after next month’s presidential elections.

Unless the winner of those elections explicitly endorses the idea that China and Taiwan are one country, the entire dialogue process between the two sides “will inevitably be affected and could even collapse,” a senior official in Beijing warned.

“The ship of cross-strait peaceful development will encounter terrifying waves or could even capsize,” Ma Xiaoguang, spokesman for the mainland’s Taiwan Affairs Office, told a news conference.

From left to right, Taiwan's 2016 presidential election candidates, People first Party's James Soong, KMT's Eric Chu, and DPP’s Tsai Ing-wen join hands at the start of their first televised debate in Taipei Sunday. (Chuck Chen/AFP/Getty Images)

The “one China” principle, agreed to in 1992, allows both sides to claim to be rightful rulers of the Chinese nation, but explicitly closes the door to the idea that Taiwan could one day become an independent nation, a concept that is anathema to Beijing.

The 1992 consensus, as it is known, was hammered out by China’s Communist Party and Taiwan’s Nationalist Party, or Kuomintang, and has underpinned a deepening of trade and diplomatic ties between the two sides, culminating in a historic meeting of the presidents in November.

At that meeting, both sides took pains to stress that the summit had only been possible because of the 1992 consensus. That was seen as a pre-election message to Taiwanese voters, and to the opposition and more independence-minded Democratic People’s Party (DPP), which has never endorsed the “one China” idea.

DPP candidate Tsai Ing-wen is the overwhelming favorite to win the Jan. 16 presidential election. She supports maintaining the status quo with Beijing and even deepening trade ties. But pressed by her main opponent, Eric Chu of the Kuomintang (KMT), at a televised debate Sunday, she declined to endorse the “one China” idea, while stressing the importance of a rational dialogue.

“As long as we have sincerity, communication, I believe cross-strait relations can be stable,” Tsai said, according to Bloomberg News. “The 1992 consensus is one option, but it’s not the only option. It is inappropriate to continue to frame it as such.”

Tsai has held talks with “persons of influence in Beijing” and is likely to have already explored some of those other options, said J. Michael Cole, a senior Taipei-based fellow at the University of Nottingham’s China Policy Institute.

The question is whether Beijing is open to compromise.

Chu’s KMT has launched a “sustained campaign of scare-mongering” in the past two or three days, Cole said, warning voters of Taiwan’s possible international isolation if the DPP wins the election.

Nevertheless, if and when Tsai comes into office in May, “China will have to decide whether it wants the whole thing to collapse and further alienate the Taiwanese public, or, for the initial period in a Tsai administration, see what she’s about and determine whether they can work with her,” Cole said.

“My guess is that they will pick the latter option and will assess what she means by ‘other ways to conduct business’ with them.”

Cole pointed out that there was a substantive dialogue across the Taiwan Strait during the initial years of the presidency of the DPP’s Chen Shui-bian from 2000 onwards, even though Chen did not support the one-China principle.

“So it would be false to assume that Beijing will never negotiate with Taipei under anything other than that framework,” said Cole, who is also editor in chief of Thinking Taiwan, a website linked to a think tank founded by Tsai.

A Chinese expert in Beijing, who spoke on the condition of anonymity since he is not authorized to speak to foreign media, said China’s latest comments were actually milder than warnings issued ahead of previous Taiwanese elections in 1996 and 2000, adding that Beijing was calmer and more practical in its approach these days.

“Both sides want to keep the current relationship,” he said. “So both sides have left room for compromise on this issue.”

But there is a risk, experts warn: that Chinese President Xi Jinping takes a harder, more nationalistic line than his predecessors, as he has on other issues of territorial sovereignty.

In that case, Wednesday’s storm warning from Beijing could turn out to be more than just hot air.

Liu Liu and Xu Jing contributed to this report.