Donald Trump is floating the possibility of dropping Washington’s “One China” policy, the diplomatic understanding on the status of Taiwan that has helped keep US-China relations relatively stable for four decades.

In an appearance on Fox News Sunday, Trump painted the possible move as an opening gambit for harder-edged negotiations with China on issues like trade and the country’s expansion into the South China Sea. The comments came just days after Trump’s tradition-breaking call with Taiwan’s president raised alarms last week in both Washington and Beijing.

Beijing has already pushed back swiftly, strongly indicating that scuttling One China is a non-option and explicitly saying that if the policy was ever placed on the negotiating table, talks over all other issues would immediately come to end. That could lead to Beijing rebuffing US calls that it do more to rein in North Korea, using its veto power at the UN Security Council to block any American-backed initiatives, and flatly refusing to engage in formal talks over climate change or trade-related issues.

Trump and his advisers may believe China is just bluffing, and that Beijing knows its economy is so intertwined with that of the US that it would literally be too costly for the country to escalate tensions with the US.

That could be a catastrophic misjudgment. Jessica Chen Weiss, a scholar of Chinese foreign relations at Cornell University, says the Chinese government’s insistence that the One China policy remain in place isn’t simply to preserve a linchpin of diplomatic relations between China and the US — it’s to help preserve its own existence.

Her argument is that since the beginning of communist rule in China, standing up to foreign interference has been a bedrock principle in the country’s political life, and that it’s not something that should be underestimated. Failing to respond to Trump’s provocative language about Taiwan could easily spark public criticism that the government was reneging on a core value and giving in to a bully from a country that much of China already distrusts.

The upshot: Beijing is far more likely to lash out at the US economically or make shows of its military might than it is to roll over on the issue of Taiwan’s sovereignty.

“The Chinese government will feel pressure from the public to take a stronger stance on Taiwan,” Weiss says. “Even though it’s not a democratically elected government, it is really concerned with popular protests that could push them out of office.”

There are signs Beijing is already taking steps to show the degree of its anger — and to offer a warning of how it could respond in the future. According to CNN, China flew nuclear-capable H-6 bombers over some of the most hotly-contested parts of the South China Sea on December 7 and December 8, just days after vetoing a US-backed UN Security Council resolution calling for a temporary truce in the war-battered city of Aleppo.

Beijing has blocked Washington’s diplomatic efforts at the UN before, but the timing of the vote and the flights suggests they could be intentional messages to Trump about what’s to come if his rhetoric and behavior continue unchanged.

Trump’s style of negotiating, in other words, is likely the entirely wrong approach to take with a rising superpower anxious to maintain its standing abroad and at home.

Trump doesn’t believe in sacred cows

A little over a week ago, Trump sparked days of controversy by taking a call from President Tsai Ing-wen of Taiwan. The call broke with the long-established protocol of the One China policy, in place since 1979, which has kept US presidents from communicating directly with Taiwanese leaders to avoid making it appear as if Washington recognized the island as an independent nation.

That agreement has great meaning to Beijing, which considers Taiwan a part of China. As my colleague Jennifer Williams explains:

The dispute between China and Taiwan goes back to 1949 and the end of the Chinese Civil War, when the defeated Nationalists fled to the island of Taiwan, leaving the communists in power in mainland China. The two territories have been governed separately ever since, with both governments claiming to be the legitimate representative of "One China" — that is, China and Taiwan. Most countries, including the US, only have formal diplomatic relations with mainland China and don't officially recognize the government in Taiwan — which is why Trump’s casual chat with the president of Taiwan, and his seemingly cavalier choice of words when describing Tsai, is so surprising, and so risky.

In the days after the call, Trump downplayed its meaning for US-Chinese relations, and suggested it was just a polite conversation. But on Sunday, Trump indicated that the call should perhaps be interpreted as more than friendly personal exchange.

"I fully understand the One China policy, but I don't know why we have to be bound by a One China policy unless we make a deal with China having to do with other things, including trade," Trump said on Fox News Sunday.

“I mean, look,” he continued, “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.”

Beijing worries that abandoning the deal could end its grip on power

Trump’s remarks made it clear that he’s willing to buck tradition as a negotiating tactic. China has not taken kindly to the suggestion, with a state-controlled newspaper calling Trump “as ignorant as a child” for his remarks on Taiwan, while the government itself took a hard public line.

“Adherence to the One China policy is the political bedrock for development of [bilateral] relations,” Geng Shuang, a foreign ministry spokesperson, said on Monday. “If compromised, there will be nothing to discuss on cooperation in major fields.”

China could do a variety of things to show the US it means business on this front, like quietly interfering with the ability of US businesses to sell goods in China. China curbed imports of fruit from the Philippines when the two countries clashed over territorial claims in the South China Sea, for example.

China could also try to give a tangible illustration of its firepower, something Beijing has actually done before to dissuade the US from deviating from One China. After Taiwan’s then-president visited Cornell University in 1995, Beijing responded by conducting missile tests in the Taiwan Strait.

China could also do things like more aggressively expand its territorial claims and defense installations in the South China Sea or block all US-backed activity at the UN through its veto power on the UN Security Council.

As Weiss explains, Beijing could be willing to take such aggressive steps because of fears of how its public would react if it failed to respond to Trump’s saber-rattling. Appearing to stand strong in the face of aggression from foreign rivals, she says, is close to a cardinal rule in Chinese politics.

“The Communist Party under Mao Zedong really founded the People’s Republic of China in opposition to foreign imperialism and interference in China’s so-called internal affairs,” Weiss says.

That’s particularly important to Chinese nationalists, who have great sway over the political dynamics of the country. And that means China is unlikely to back down on Taiwan. “China would be willing to suspend all negotiation rather than let him move the status quo on the issue,” she says

If that’s true, Trump’s apparent willingness to roll the dice on abandoning decades of tradition out of a belief that his negotiating skills could give the US a leg up over China could in fact leave Washington with a weaker hand that it had before. Trump may not want to admit it, but the US can’t just get it wants simply by pretending the rules of the game don’t exist.