Note: This analysis of air incursions into Taiwan’s air defense identification zone is focused on the period from September 2020 to September 2021, while also accounting for the large-scale incursions between October 1-4, 2021. This article serves as an update to a previous article published in the Global Taiwan Brief in April 2021.
In September 2020, Taiwan’s Ministry of National Defense (MND) began publishing regular, detailed reports on Chinese military air incursions into Taiwan’s air defense identification zone (ADIZ). People’s Republic of China (PRC) military flights into Taiwan’s ADIZ have continued for over one year, and the incursions have become a near-daily occurrence. Between September 17, 2020 and September 30, 2021, PRC military aircraft entered Taiwan’s ADIZ on nearly 250 days. Almost all of these incursions took place in the southwestern part of the ADIZ near Taiwan-held Dongsha Island (東沙島) in the South China Sea; only a few occurred in the Taiwan Strait proper. Many of the larger-scale incursions were preceded by some development related either to US-Taiwan relations or Taiwan’s international space.
The significant escalation in incursions in early October 2021 has demonstrated how Chinese intimidation of Taiwan continues to change the status quo between Beijing and Taipei. In the first four days of October—including the PRC’s October 1 National Day holiday—almost 150 aircraft breached Taiwan’s ADIZ, a higher count than the entire month of September. During the second incursion on October 4, 34 J-16 fighter jets entered Taiwan’s ADIZ, which is more aircraft than the total number that breached the ADIZ in May, July, and August.
The most troubling aspect of the ADIZ incursions is that the Chinese military has grown more brazen since September 2020. Throughout 2021, the use of J-16 and J-10 fighter aircraft has increased, and they have now become a regular feature of the incursions. The flying of nuclear-capable bombers, such as the H-6K, is now also a normal occurrence in Taiwan’s southwestern ADIZ. Studying these incursions allows us to draw lessons moving forward about the defense of Taiwan, as well as patterns in Chinese military coercion directed against Taiwan.
A Shift in Emphasis?
In the timeframe from September 17 – December 31, 2020, the Chinese military kept its patterns and numbers relatively stable. On only a few occasions did the number of aircraft exceed five. Fighter jets, like the J-16, were used infrequently. The most noteworthy of those incursions, in which People’s Liberation Army (PLA) aircraft crossed the centerline of the Taiwan Strait, occurred in direct response to a visit to Taipei by then-Under Secretary of State for Economic Growth, Energy, and the Environment Keith Krach, who attended former President Lee Teng-hui’s funeral in September 2020. The purpose of that exercise, as expressed in the PRC, was to thwart “Taiwan independence.” After two consecutive days of drills in the Taiwan Strait, the incursions reverted back to their usual tempo.
After President Joseph Biden took office, the incursions became more provocative in nature, and the use of fighter jets and nuclear-capable bombers increased significantly throughout 2021. During Biden’s first days in office, the PLA conducted two consecutive days of exercises in Taiwan’s southwestern ADIZ, which simulated an attack against the nearby USS Theodore Roosevelt carrier strike group. This two-day exercise, which included 28 aircraft, marked the highest number of aircraft to enter Taiwan’s ADIZ since September 2020. During Biden’s first month in office, fighter jets and nuclear-capable bombers were used in ten incursions—a significant bump in usage from 2020. Also, for the first and only time in the reporting period, the MND noted that US aircraft breached Taiwan’s ADIZ on January 31 and February 1.
Before Biden took office, these incursions started to become a part of the “status quo” in cross-Strait relations. They now have become a regular part of Chinese coercion against Taiwan. Given the increase in the use of fighter jets throughout 2021, what once would have been considered a major news headline is now a routine occurrence for the Taiwanese military. In 2020, J-16s made up less than 15 percent of the aircraft sorties, and J-10s under five percent. However, in 2021, J-16s have increased to under 30 percent, and the J-10 under 10 percent. More troublingly, the J-16—the PRC’s most advanced fighter jet in operation—is now the most flown aircraft in these incursions. The Y-8 anti-submarine warfare (ASW) variant ranks second, and the Y-8 electronic warfare (EW) variant, Y-8 reconnaissance (RECCE) variant, and J-10 fighter jet are all fighting for third place. However, it should be noted that the Y-8 ASW appears more frequently and regularly, often flying solo missions—whereas the J-16s are used in the larger-scale incursions in higher numbers, as occurred in early October 2021. The increase in the use of fighter aircraft again marks a shift in the status quo.
While the incursions are now a regular element of cross-Strait relations, the prevailing media narrative around them has been their seemingly reactive nature. Whenever there was a major event related to Taiwan’s international space, the Chinese military would respond with a large-scale incursion immediately after. As mentioned above, this pattern held for Krach’s visit to Taipei. It also occurred after Biden’s inauguration, which was attended by Taiwan’s de facto ambassador Hsiao Bi-khim, and a transit by the USS Theodore Roosevelt through the area. The October 2021 incursions occurred around the same time as a major joint naval exercise near Japan, in which the navies of the United States, United Kingdom, Japan, Netherlands, Canada, and New Zealand participated.
It is not a coincidence that most of the 20 double-digit incursions occurred right after a major event. In March, 20 Chinese aircraft breached Taiwan’s ADIZ right after Washington and Taipei signed an agreement to establish a Coast Guard Working Group. However, from the Chinese perspective, this was reportedly an exercise to simulate an attack on US ships in the region. A large-scale April incursion—which included 25 aircraft, at the time the most ever used in such an event—came right after Secretary of State Tony Blinken signaled US support for Taiwan in the face of Chinese aggression. Then, in June 2021, 28 aircraft (the highest count at the time) flew through Taiwan’s ADIZ after the Group of Seven released the Carbis Bay Communiqué, which “underscore[d] the importance of peace and stability across the Taiwan Strait, and encourage[d] the peaceful resolution of cross-Strait issues.” Interestingly, between these April and June incursions, not a single incursion spiked into the double digits. In September, after Taiwan announced that it had submitted its application to join the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP)—just days after Beijing had announced its own bid—24 Chinese aircraft breached Taiwan’s ADIZ.
Looking at the trends in incursions in the past year, it is clear that some occurred in direct response to alleged “Western provocations,” or actions by so-called “Taiwanese independence” forces. However, these exercises require planning and coordination that cannot occur in the blink of an eye. It is likely that some of these exercises are pre-planned but held until the right moment so that Beijing appears to be responding—and more importantly, punishing—Taiwan for its actions. (Or, as may be the case much of the time, for Taiwan seeking to participate in world affairs.) The October show of force was undoubtedly a long-planned exercise to celebrate the PRC National Day holiday with a demonstration of Chinese military power.
Beyond the large-scale incursions, summer 2021 marked the beginning of a new development in incursion activities. In 2020, only one day—October 28—saw two incursions in the same day. The end of January (January 28 and 31) had two such days. However, between July and September, there have been seven double-incursion days (July 2, July 12, August 12, September 8, September 19, September 23, and September 26). Between October 1-4, there were three double-incursion days. It is possible that the Chinese military is testing out a new element in its coercion against Taiwan, and giving pilots additional training during different times of the day. Increasing the number of incursions per day would mark a new phase in the ADIZ breach tactic. Throughout 2021, the use of J-16s, J-10s, and H-6s has become a regular part of the incursions. Now, it is possible that Taiwan will have to deal with double-incursion days as a new element of its defense planning. However, there is a stark difference between two Y-8 ASW incursions on one day, and two large-scale incursions featuring a variety of aircraft. The status quo in respect to the ADIZ is always evolving and changing.
The Success of Reporting
After one year of Chinese air incursions, it is clear that they are not going away. Regular, near-daily air incursions into Taiwan’s southwestern ADIZ are now a part of the status quo in cross-Strait relations. As 2021 draws to a close, it will be interesting to see whether the PLA continues with its current patterns, or if double-incursion days become more regular. Another potential change could be the location of the incursions. There will come a point when the Chinese military’s lessons learned from conducting these operations and exercises hit their peak. After so many incursions by solo Y-8 ASWs or Y-8 EWs, there’s only so much more that can be improved (outside the obvious benefit of keeping pressure on Taiwan, and forcing changes in MND policies due to fuel costs). It is possible that these incursions could expand to more troubling areas—especially the Taiwan Strait proper—or longer missions to Taiwan’s east coast through the Bashi Channel, which occur infrequently. No incursions have occurred in the northern part of the ADIZ, which would draw in Tokyo given that many Japanese islands are close to Taiwan’s northern coast.
For Taiwan, the act of releasing regular reports on PLA incursions has proven to be a success. By releasing easily digestible reports with the number and type of aircraft along with the flight paths, Taipei is shedding light on one particular aspect of Chinese coercion. These reports—and the concept of air incursions—are much easier to understand and comprehend than a longer report on Chinese misinformation, or even economic coercion. The world knows that China regularly pushes the boundaries of acceptable actions, but without consistent and simple reporting, it is hard to keep attention on the issue. For Taiwan, this lesson could be taken and applied to other aspects of Chinese coercive actions.
The main point: Evaluating one year of Chinese military aircraft incursions into Taiwan’s air defense identification zone has demonstrated a steady rise in escalatory behavior, with an increase in the number of large-scale incursions and the use of fighter jets and nuclear-capable bombers. These ADIZ incursions have received much public attention and international condemnation, but they are only one example of Chinese military coercion against Taiwan.
 Distinct from territorial airspace, many states assert an ADIZ extending from their territory—a concept defined by the US Federal Aviation Administration as “an area of airspace over land or water, in which the ready identification, location, and control of all aircraft […] is required in the interest of national security.”
 Calculations based on author’s research.