Last Friday, president-elect Donald Trump broke with nearly 40 years of precedenceby talking over the phone with President Tsai Ing-wen of Taiwan. Regardless of who made the call, reporting by The Washington Post indicates that it was planned in advance and could be a precursor of bigger shifts in America’s Taiwan policy under the Trump administration. Beijing responded with relative calm and restraint, releasing an official statement that placed blame on Taiwan and downplayed the policy impact of the call.

While many American foreign policy experts were shocked by Trump’s action, several conservative commentators have voiced their support, arguing that America’s Taiwan policy needs a recalibration after years of neglect under the Obama administration.

Trump’s Taiwan phone call isn’t that dangerous by itself, and China will not risk a conflict over it. But the call could be insidious if it signals a shift in America’s role in the cross-strait relationship away from that of stabilizer. Of course, one action does not make a trend and the call does not rise to the level of policy. However, based on Trump’s repeated jabs at China, a Republican party platform that took a harder line than its predecessors, and the foreign policy experts that have praised the Taiwan call, the United States is headed for a period of heightened tension with China that carries very high potential costs if things spiral out of control.

Traditionally, the United States has been a responsible actor in the feud between China and Taiwan. After Chinese nationalist forces under Chiang Kai-shek fled to the island in 1949, the United States signed a defense treaty and deployed military forces to prevent Mao Zedong from attacking the island. The United States also discouraged Chiang Kai-shek from starting a war by attacking mainland China, though Taiwan and China did engage in small-scale armed clashes.

Recently, U.S. policy toward Taiwan was known as “dual deterrence,” which first took form during the 1995—96 crisis in the Taiwan Strait. Under dual deterrence the United States issued a combination of warnings and reassurances to both China and Taiwan to prevent either from unilaterally changing the status quo. While the viability of dual deterrence is challenged by China’s growing military power, it has successfully maintained a peaceful state of affairs. And while it is impossible to capture all of the complexity of the Taiwan-China‑U.S. relationship here, it is fair to say that the United States has been a force for stability.

Trump’s Taiwan call is a major departure from that paradigm. Instead of the United States maintaining stability, the president-elect is injecting uncertainty via this very high-profile break with precedence. This does not absolve China of its destabilizing, coercive actions toward Taiwan, but such behavior is consistent with China’s past behavior whereas the Trump phone call is a break with the past. If Trump continues with these types of actions after becoming president, then the United States could usher in a dangerous period in the cross-strait relationship. Repeatedly making strong displays of U.S. support for Taiwan that break with generally accepted norms creates an environment ripe for uncertainty and miscalculation.

Whether or not a closer U.S.-Taiwan relationship is in America’s long-term interests, there are ways to go about improving the relationship that avoid destabilizing action. For example, the Trump administration could restore annual arms sale talks with Taiwan that were cancelled in 2001. This would anger Beijing, but arms sales have been a regular fixture of U.S.-Taiwan relations, so Beijing would know what to expect. This would also increase stability, as the weapons systems improve Taiwan’s ability to deter armed conflict. It would also signal a deepening of U.S.-Taiwan ties without injecting as much uncertainty into the cross-strait relationship.

China is no longer a weak actor that can be easily cowed into submission. During the last crisis in the Taiwan Strait, 20 years ago, China’s economy was still finding its footing and its conventional military forces were clearly outmatched by the United States. But a lot has changed in two decades. China is now has the world’s second biggest economy and improvements in its military forces means it can inflict a good deal of pain on the United States should a crisis spiral into conflict. Trump and his incoming administration need to appreciate these strategic realities. If they want to improve relations with Taiwan, it must be done in a measured, responsible way.