China's warplanes have all but erased the dividing line in the Taiwan Strait, creating a dangerous new normal

• China's military has flown into Taiwan's ADIZ almost every day since 2020.
• Crossings of the median line have soared, effectively erasing it altogether.
• The incursions, as well as large-scale military drills, wear down Taiwan's military.

China's warplanes are pressuring Taiwan and have all but eliminated an important dividing line, with near-daily incursions creating a dangerous new normal.

Since 2020, Taiwan has released regular, almost daily updates on incursions in its air defense identification zone by Chinese military aircraft. It has also documented continuous Chinese efforts to degrade the Taiwan Strait median line established in 1955.

Researchers Thomas J. Shattuck, a non-resident fellow at the Foreign Policy Research Fellow, and Benjamin Lewis, co-founder of the PLATracker organization, have tracked increasingly bold Chinese behavior. A review of data from Taiwan revealed that ADIZ incursions over the past four years have shown a growing rejection of the unofficial dividing line put in place for deconfliction.

China's military incursions into Taiwan's ADIZ and its crossings of the median line in the Taiwan Strait have skyrocketed, with the ADIZ incursions climbing from an average of 2.56 aircraft per day four years ago to 11.63 now.

A nation's ADIZ extends far beyond its territorial airspace, but the area is closely monitored for national security purposes. When Chinese aircraft enter Taiwan's de facto ADIZ, it dispatches combat air patrol (CAP) aircraft in response.

In 2021, the Chinese military flew 972 aircraft into Taiwan's ADIZ, and that number nearly doubled in 2022. 1,703 aircraft were recorded in 2023. And 2024 looks to have a record-breaking number, with over 2,000 aircraft documented as of September. They're also no longer limited to a corner of the ADIZ.

Crossings of the median line have become increasingly common since August 2022, when then-House Speaker Nancy Pelosi controversially visited Taiwan, and China has been steadily erasing it altogether. In a recent drill surrounding Taiwan, 111 Chinese warplanes crossed it, marking a single-day high. A few years ago, Taiwan might see hundreds cross the line but over months.

"We've become desensitized to high numbers of the military aircraft flying across the median line of the Taiwan Strait," Shattuck told Business Insider. "Five years ago, that was unheard of. Now, it's just another Thursday."

China claims Taiwan as its own territory and hasn't ruled out using its growing military to achieve unification, raising concerns in Taipei, the US, and other Western nations that China could one day enact a blockade or full-scale invasion of Taiwan to force it to give in to Beijing's authority.

Beijing's tactics run the gamut of intimidation and coercion, including political and economic pressure and massive military exercises aimed at forcing the Taiwanese people to reject independence.

Recently, two joint-force drills, "Joint Sword 2024-A" and "Joint Sword 2024-B," saw the Chinese People's Liberation Army effectively surround Taiwan, simulating how it could blockade key ports and areas, assault maritime and ground targets, and seize territory.

During "Joint Sword 2024-B," Taiwan's defense ministry said that a record number of Chinese warplanes, over 150, flew into its ADIZ in one day. In response, Taiwan's new president, Lai Ching-te, said China aims "to undermine stability and the status quo."

Chinese incursions are tiring out Taiwan's forces

The near-daily ADIZ incursions aren't just changing the status quo in the area; they're also exhausting Taiwan's military.

In October 2020, then-Taiwanese Minister of National Defense Yen Teh-fa said Taipei's air force and navy spent almost $1 billion monitoring Chinese sorties. Since then, Taiwan has adjusted its responses to the ADIZ violations in order to reserve resources, but it is still taxing.

In this tough situation, "the concern is the continued degradation of Taiwan's military assets and the draining of Taiwan's military personnel," Shattuck said, explaining that China "exploits" Taiwan's military capabilities "by flooding the field and forcing Taiwan to choose what things deserve a response."

That degradation could ultimately leave Taiwan's military weakened should one of China's large-scale drills suddenly become the real deal, and with US aid to Taiwan "long-delayed and overdue," Shattuck said, it could hamper Taiwan's readiness.

"The median line of the Taiwan Strait—a de facto boundary that created some semblance of cross-Strait stability—is no more" and "Taiwan cannot push back on all fronts against these PRC incursions," Lewis and Shattuck wrote recently.

This is an attritional fight, they said, arguing that while Chinese military activities around Taiwan "have become normalized and are a part of the ever-deteriorating status quo in the Taiwan Strait," Taipei and Washington still have cards to play.

Taiwan has spent years navigating tricky relations with Beijing, which is opposed to the ruling Democratic Progressive Party and has labeled Lai a "separatist."

During his inauguration speech, Lai promised to uphold Taiwanese democracy as a global beacon, calling on China to cease its intimidation against Taiwan. The speech further inflamed relations, and "Joint Sword 2024-A" shortly followed. Lai toned down rhetoric during his National Day speech earlier this month, demonstrating restraint in calls for peace and understanding.

"Lai's National Day speech indicates that Taipei is attempting to find ways to offer an olive branch to China while maintaining its assertions of Taiwan's de facto sovereignty," Amanda Hsiao, Crisis Group's Senior Analyst for China, told BI. But China's reaction, "Joint Sword 2024-B," was intense and sent a message.

Regardless of what Lai says or how he approaches relations, Shattuck said, China doesn't trust him. 

"It no longer matters what sorts of olive branches a DPP president may extend because Beijing will not accept them," he said, explaining that "Beijing is attempting to accelerate its squeezing of Taiwan's own sovereign territory." That has implications for Taiwan and its international partners.

As the Chinese military continues its incursions in Taiwan's ADIZ, Washington and its allies "need to remain vigilant in protesting these activities so that it is clear that military coercion of Taiwan is unacceptable," Shattuck said.

"It is unrealistic to argue that Taiwan or the United States will be able to stop the PRC aerial and maritime incursions around Taiwan," he and Lewis wrote, but there are options. "Washington," they said, "should work to elevate Taiwan's ability to track the situation around its territory and provide it with the necessary resources to push back as needed."