Recent weeks have seen significant developments in the awkward three-way relationship between Taiwan, China and the U.S. First, President Donald Trump signed the Taiwan Travel Act, which made it American policy to encourage greater high-level contacts — including defense and national security ones — with Taiwan, despite the displeasure those contacts will surely incur from China. Second, Taiwan’s spy chief warned that a more empowered and assertive Chinese government, under the leadership of President Xi Jinping, is now relying on “more sharp-elbow rhetoric and tactics” to deal with an island it considers a renegade province. North Korea and the South China Sea may be the Asian hot spots getting the most attention today. But the waters are getting choppy in the Taiwan Strait, as tensions rise and the threat of crisis grows.

Hostility between Taiwan and the mainland dates back to 1949, when the remnants of Chiang Kai-Shek’s Nationalist regime took refuge on the island after losing the Chinese civil war to Mao Zedong’s Communists. For more than two decades, the U.S. protected Taiwan and recognized Chiang’s government as the sole representative of China before shifting its allegiances and diplomatic recognition to Mao’s regime in the 1970s. Since then, Taiwan has continued to exercise de facto sovereignty but not de jure independence, and all but a small number of countries have transferred diplomatic recognition to Beijing. The U.S. has pursued an equally ambiguous policy of not recognizing Taipei diplomatically but selling it weapons for self-defense. It has also pledged — albeit in very hedged and murky terms — to prevent China from using force to bring Taiwan to heel.

This situation has never been comfortable, but it has nonetheless endured longer than almost anyone would have predicted. And from 2008 to 2016, China pursued the goal of unification primarily through carrots rather than sticks, by working with the comparatively friendly government of Ma Ying-Jeou to increase economic, cultural and political ties. The idea animating this policy was that weaving a denser web of interactions between Taiwan and the mainland might lead to the eventual peaceful reabsorption of the island.

For years, Chinese leaders could reassure themselves that Taiwan’s anomalous status was tolerable, because in the long run, unification was simply a matter of time. Now, however, they have to face the possibility that time is not on their side after all.

In Taiwan, the tide is increasingly turning away from the idea of unification with China. Polls show that a large majority of the population now considers itself Taiwanese rather than Chinese. Moreover, as Taiwanese democracy has matured and its citizens have seen how China has slowly squeezed the life out of Hong Kong’s political institutions, public support for unification has dropped sharply. These trends were offset for much of the past decade by Ma’s generally conciliatory policy. But the election of Tsai Ing-Wen in 2016 brought to power the Democratic Progressive Party, which traditionally supported outright independence. For Beijing, any declaration of Taiwanese independence would cross a bright red line, perhaps triggering the use of force. And although Tsai has since pledged to respect the status quo, suspicions persist in Beijing that she will maneuver Taiwan toward a formal break.

China’s incentives for a sharper policy have simultaneously been growing. The awesome rise of Chinese power over the past few decades has given Beijing better options for coercing — whether economically or militarily — a wayward Taiwan. Most analysts still agree that China would face enormous difficulties in invading and conquering Taiwan, especially if the U.S. intervened in Taipei’s defense. But Beijing’s increasingly impressive naval, air and missile capabilities have nonetheless given it a bigger stick to wield, and its development of anti-access/area denial, or A2/AD, capabilities have raised the prospect that U.S. forces coming to Taiwan’s defense might suffer enormous losses. As a 2015 Rand Corp. study concluded, the U.S. is approaching, if it has not already reached, the point at which the defense of Taiwan might be too costly to contemplate. 

Rising Chinese nationalism is also making it more difficult politically for Beijing’s leaders to defer the question of Taiwan’s status indefinitely. And then there is Xi Jinping. China’s supreme leader clearly aspires to claim great-power status for his country, something that is incompatible with the continuing humiliation imposed by Taiwan’s separation. He and other Chinese officials have stated that they will not wait forever for Taiwan to return to Beijing’s control. A leader who seems to believe that both he and his country have a great historical destiny to fulfill might very much like to have unification with Taiwan become part of his legacy.

After Tsai’s election, Beijing thus restricted tourism to Taiwan and imports of key Taiwanese goods, such as fish, in an effort to punish the island economically. Beijing has upped its military presence in the waters and airspace around the island, and ostentatiously sent its aircraft carrier through the strait as an unsubtle reminder of Chinese military power. Retired Chinese military brass have urged the government to plan for an invasion of Taiwan. Experts still believe an outright military showdown is unlikely, but the cross-strait relationship nonetheless appears to be entering another period of heightened tensions.

Those tensions will pose a challenge for the U.S. In the years after the opening to Mao’s regime in 1971, U.S. officials initially saw Taiwan as an unwelcome irritant to a budding geopolitical relationship with the mainland. But China was a tacit Cold War ally back then. Today, China represents perhaps the greatest threat to American interests and influence, both in the Asia-Pacific and globally, and Taiwan is a critical frontline state. It would not serve U.S. interests for Taiwan to provoke a military crisis with the mainland; it would also be a strategic disaster were Beijing to successfully coerce or compel reunification with Taiwan.

These competing pressures dictate a careful balancing act. The U.S. should continue to caution Taipei against making destabilizing moves toward independence. It should probably not inflame the situation by once again extending formal diplomatic recognition to Taiwan or otherwise revisiting the “one China” policy, as incoming national security adviser John Bolton has sometimes suggested. Yet it should nonetheless help strengthen the island against aggression or coercion.

This means investing in the U.S. military capabilities necessary to burst China’s A2/AD bubble should conflict erupt. It means pushing Taiwan to acquire and emphasize its own A2/AD capabilities to frustrate any Chinese military operations until the U.S. can intervene. It means helping to strengthen Taiwan diplomatically and economically by encouraging stronger ties with other U.S. allies and partners in the Asia-Pacific.

Finally, it means pushing ahead with the expanded high-level contacts and visits called for by the Taiwan Travel Act. Beijing will fulminate against those contacts and try to punish Taiwan economically or diplomatically in their wake. But they will give U.S. officials better insight into the state of Taiwanese politics and security, and they will send the crucial message that more aggressive Chinese behavior will not weaken but strengthen America’s relationship with a democratic Taiwan.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.