Breaking The Barrier: Four Years Of PRC Military Activity Around Taiwan – Analysis

By Thomas J. Shattuck and Benjamin Lewis

(FPRI) -- On September 17, 2020, the Republic of China’s (Taiwan’s) Ministry of National Defense (MND) released its first-ever “real-time military update” documenting two incursions into the country’s air defense identification zone (ADIZ) by two Y-8 anti-submarine warfare aircraft from the People’s Republic of China (PRC) the day prior. An ADIZ is “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,” essentially a buffer zone before an aircraft reaches a country’s defense area or territorial airspace. For Taiwan, its ADIZ includes the all-important median line of the Taiwan Strait, a line created in 1955 by General Benjamin Davis, Jr., that divides the waterway in half, originally meant to deconflict military operations by Taiwan and China.

Since 2020, Taiwan’s ADIZ has become the center of the PRC’s military activity around Taiwan. That first report in 2020—containing a map of Taiwan’s ADIZ, the approximate flight paths of the aircraft, and photos of the aircraft taken by Taiwan’s air force—started a new practice in Taipei for publicizing military pressure and coercion by Beijing.

The first few reports documented a People’s Liberation Army (PLA) military exercise in the Taiwan Strait conducted in response to a visit to Taipei by then-US Under Secretary of State for Economic Growth, Energy, and the Environment Keith Krach. A similar exercise occurred in August 2020 in response to then-US Secretary of Health and Human Services Alex Azar’s visit to Taipei.[1] The MND acknowledged the PLA exercise in response to the Azar visit, but it did not begin the formal reports until the Krach visit. In summer 2020, leaders in the PRC made the decision to primarily use airpower to coerce Taiwan in the military space, using favorable events for Taiwan, like high-profile visits, as a pretext to take such actions to punish Taipei.

Over the last four years, these reports have been the most public-facing effort by the MND to demonstrate the near-daily threats that Taiwan faces from the PRC. They have changed in format, forbetterandworse, during these four years. They also have shown changes in how Beijing attempted (and still attempts) to utilize its larger and better resourced military to force changes to Taiwan’s political behavior. In 2021, the PLA flew 972 aircraft within Taiwan’s ADIZ; in 2022, it was 1,738; and 1,703 in 2023; the number currently stands at 2,002 for 2024 (as of September 10, 2024).

The PRC ADIZ activities since 2020 have occurred in five phases, each with its own distinct behavior, level of activity, and focus. Each phase built on the previous one to amplify the various pressure points on Taiwan’s military. Over the last four years across the five phases, the average daily number of aircraft tracked in the ADIZ has skyrocketed: in phase one, 2.56 aircraft per day; in phase two, 6.06; in phase three, 5.17; in phase four, 3.51; and in phase five, 11.63.

Phase 1 (September 2020-July 2022): The New Model of Pressure

While the first reports identified PLA incursions across the median line of the Taiwan Strait, the primary area of activity during this first phase was in the southwestern portion of the ADIZ in the South China Sea near Pratas/Dongsha Island. The southwestern part of the ADIZ is the farthest possible point from Taiwan island within the ADIZ. Even though the flights were relatively near the Taiwan-occupied islands in the South China Sea, they were far enough away from Taiwan proper that they did not necessarily pose an immediate threat.

Beyond the geography, the types of aircraft used point to the primary purpose of navigation operations, and most of those drills were relatively smaller in size (compared to present-day operations). As the PLA presence in the ADIZ became more established, the number of aircraft increased steadily, and the types and diversity of aircraft also changed.

The increased number of aircraft and greater sophistication had a negative effect on Taiwan’s military. By October 2020, then-Minister of National Defense Yen Teh-fa said that the air force and navy had spent over NT$30 billion, or8.7 percent of the MND’s budget,to intercept and monitor the sorties, including nearly 3,000 Taiwanese sorties. Yen noted that the number of Taiwan Strait median line crossings was thehighest since the 1990s. Because of these figures—and the effect on Taiwan’s pilots and aircraft—the MND changed its policies. In March 2021, the MND decided that the air force would not scramble aircraft to intercept every single PLA sortie, but instead, it would track those aircraftusing ground-based missiles. The age of Taiwan’s aircraft resulted in high maintenance costs, so the practice was not sustainable. At the time, given the situation, the MND changed its mindset to one of a “war of attrition.” Notably, on March 26, 2021, Taiwan tracked the largest-ever (at the time) incursion of twenty aircraft. The day before, Washington and Taipei inked a memorandum of understanding to establish aCoast Guard Working Group. Throughout this phase, the largest incursions directly correlated to a Taiwan-specific event.

However, the pressure on Taipei continued to increase. A notable example of this phenomenon occurred in October 2021 during the PRC’s Golden Week, during which 150 aircraft entered the ADIZ, including 56 on October 4, 2021—still the highest single-day total on record. Phase one marked the beginning of a new PRC pressure campaign against Taiwan, which would evolve over time.

Phase Two (August 2022-March 2023): The Turning Point

The pattern of PLA activity within Taiwan’s ADIZ was relatively predictable for approximately two years. The focus in the southwestern ADIZ did not really change. Then, in August 2022, then-US House Speaker Nancy Pelosi traveled to Taiwan for a meeting with then-Taiwan President Tsai Ing-wen. That visit—a political event elevating Taiwan’s stature in international politics—changed the military status quo in the Taiwan Strait. Since that visit, the PLA ADIZ activity has primarily centered in the Taiwan Strait proper—no longer the far-off southwestern part of the ADIZ. The PLA essentially erased themedian lineof the Taiwan Strait after almost seventy years of tacitly following the division despite never officially acknowledging or accepting it. Between 1955, when the so-called Davis Line was initially drawn, and 1999, no PLA aircraft crossed the line. In 1999, after President Lee Teng-hui said that relations between Taipei and Beijing were“special state-to-state” relations, PLA aircraft crossed the median line of the Taiwan Strait.

It took another major political event—Pelosi’s visit to Taiwan—to create another significant change in the Taiwan Strait. Since Pelosi’s visit, the PLA now has an almost daily presence in the Taiwan Strait, regularly crossing the median line. The Pelosi visit did not just change the geography of the pressure; it also changed the number of aircraft operating in the ADIZ and the scale and complexity of the operations.

In direct response to the Pelosi visit, the PLA conducted a large-scale joint exercise around Taiwan. The exercises, the largest ever conducted by the PLA around Taiwan, took place in seven zones surrounding the island. Throughout August, the PLA fired at least four missiles over Taiwan’s atmosphere and sent over 440 aircraft into the ADIZ, with more than 300 of those aircraft crossing the median line of the Taiwan Strait. The scale of PLA activity around Taiwan in August 2022 remains the highest ever recorded for a single month and was the start of a near-permanent increase in the intensity of Beijing’s coercion campaign.

During the exercises, the MND began releasing the number of People’s Liberation Army Navy (PLAN) vessels tracked around Taiwan and aircraft operating on the west side of the median line. This change in methodology was indicative of both the developing scale of the PLA’s air activities and the increasingly joint nature of the PLA’s operations.

Beijing’s post-August 2022 strategy focused on erasing the median line, with more than five hundred crossings taking place by the end of the year. Simultaneously, the diversity of aircraft tracked operating inside the ADIZ continued to increase, as did the complexity of the operations they were conducting. This included aerial refueling drills and frequent “joint air-sea patrols” around Taiwan. In September 2022, the MND began releasing information on PLA uncrewed aerial vehicles (UAVs) inside the ADIZ. While UAVs were confirmed inside the ADIZ as early as two months prior, uncrewed airframes often served as Beijing’s favored tool to expand its operational reach. UAVs were frequently the first type of aircraft to fly in areas previously avoided by manned airframes. The Pelosi visit provided the PLA with the rationale to elevate its coercion of Taiwan, demonstrating the connection between political events and coercion.

Phase Three (April 2023-November 2023): Expanding Coverage

Like the second phase, the third phase began with a high-level political event related to Taiwan. And again, a new phase began because a U.S. House Speaker, Kevin McCarthy, met with Tsai, this time in California during her stopover visit in April 2023. This phase expanded PRC pressure into the naval domain with increased PLAN and Chinese maritime law enforcement activities around Taiwan.

In response to the meeting, Beijing announced a three-day “special joint patrol and inspection operation” in the Taiwan Strait, during which Chinese maritime law enforcement vessels would stop and inspect ships in the area. While no Taiwan-flagged vessels were stopped during the operation, it did set a new precedent for PRC pressure against Taiwan that was eventually used in February 2024 near Kinmen when theChina Coast Guard (CCG) stopped and boarded a Taiwanese yacht.

On April 8, 2024, the PLA Eastern Theater Command announced the three-day Joint Sword exercise around Taiwan. The exercise was intended to test the PLA’s ability to rapidly establish control over the air and sea, and most notably included fighter aircraft launched from the Shandong aircraft carrier deployed in the Western Pacific.

Over the three days of operations, the PLA sent more than 130 aircraft into the ADIZ, including 19 launched from the Shandong. The MND likewise reported more than 150 PLAN vessels operating around Taiwan, the highest number since August 2022, including a major grouping of vessels along the median line on April 10.

Following Joint Sword 2023, the PLA expanded the geographic scope of its “routine” activities around Taiwan. This included an increasing number of sorties to the northeast, east, and south of the island, and continuing flights over the median line and into the southwestern ADIZ. Likewise, the PLA maintained and gradually increased its elevated naval posture on all sides of Taiwan.

At the same time, the overall scale of the PLA’s activities increased, with month-to-month total numbers of aircraft surpassing that of 2022 until November 2023.

Phase Four (December 2023-April 2024): Pre- and Post-Election Pressure

In the lead-up to Taiwan’s January 2024 presidential and legislative elections, there was another development in PRC aerial coercion against Taiwan in the form ofballoonslaunched from the PRC. Some were detected within Taiwan’s ADIZ, while others flew over the island of Taiwan itself, including direct overflights of military installations. The balloons were a notable addition to the ADIZ reports, but it is unclear how many were detected before their inclusion in the reports. Before December 2023, balloons were spotted over other parts of Taiwan and even crashed on the outlying island of Dongyin. The balloons in this phase, however, are not the primary defining feature.

Most notably, the PLA significantly reduced the scale of its air operations around Taiwan to levels not seen since before August 2022. Only 238 aircraft were tracked inside the ADIZ from December 2023 to February 2024, compared to 446 aircraft during the same timeframe twelve months prior. Beijing likely ordered a reduction in its coercive activities to prevent accusations of voter intimidation going into Taiwan’s presidential elections. The apparent “standdown” stopped around March 2024 when the activity began increasing back to pre-election period levels.

On Taiwan’s side, the MND changed the format of its ADIZ report, including what information was shared publicly. The change removed the specific flight paths of the PRC aircraft as well as the types of aircraft tracked in the ADIZ. Instead, the new reports included a box that documents the number of aircraft, the timeframe of the flights, and the distance of the aircraft to the closest city in Taiwan.

Phase Five (May 2024-Present): The Beginning of the Lai Ching-te Era

On May 20, 2024, Taiwan inaugurated a new president, Lai Ching-te, who served as vice president during Tsai’s second term. His inauguration marks the beginning of the current phase of ADIZ activity. This phase is primarily characterized by an unprecedented increase in activity across all areas of pressure in the air and at sea. Immediately after his inauguration, the PLA conducted a military exercise, dubbed Joint Sword 2024a, which saw concurrent air and naval operations from the PLA and law enforcement drills by PRC maritime law enforcement targeting the outlying islands. From May 23 to 24, the PLA sent eighty-two aircraft into the ADIZ, with forty-six aircraft crossing the median line in a single day.

Since President Lai’s inauguration, PLA activity has in some cases come close to the scale of August 2022, with more than 430 aircraft tracked in the ADIZ in July 2024. As of September 10, more than 2,000 aircraft have been tracked inside the ADIZ since the start of 2024, the highest annual total of ADIZ incursions on record. Of those, more than 1,400 were tracked since Lai’s inauguration.

This increase in activity has also brought an overall rise in activity in every area of the ADIZ: southwest, Taiwan Strait, east, north, and outlying islands. Now, almost every day, Taiwan is surrounded by PRC military assets in greater numbers than ever before. This surge in activity puts an additional strain on Taiwan’s comparatively less-resourced military and furthers Beijing’s goal of normalizing its military presence around the island. Theincrease in activity east of Taiwandemonstrates a higher level of sophistication in operations as maintaining an aerial presence off Taiwan’s east coast would be necessary during a military invasion of the island.

On September 1, 2024, the MND changed its daily reports again to include the general coordinates of the PLA’s activities and the boundary of Taiwan’s contiguous zone and territorial airspace. These specific changes are an improvement to the previous version, but the reports continue to exclude specific information on the types of aircraft and vessels inside the ADIZ.

Conclusion and Recommendations

When the MND began releasing these reports four years ago, Taipei’s transparency efforts were innovative. They publicly cataloged PRC military actions throughout East Asia. The information provided governments and their leaders with a rationale for increasing their public support for Taiwan. However, other countries facing pressure from the PRC, such as Japan and the Philippines, now release similar information, and Taiwan has competition in the battle for “airtime.” Taipei must take advantage of its broader international support, particularly from the United States, before the PRC once again changes the status quo in the Taiwan Strait and increases its pressure against Taiwan. Improving the quality and type of information provided about the PLA’s activities around Taiwan would serve Taipei’s efforts to position itself as the “front line” against Beijing’s territorial ambitions in the region. Changing the information released in the reports without a clear rationale diminishes the integrity of the MND’s transparency. It is in Taipei’s best interest to share as much information as possible so that it makes it more difficult for individuals or governments to minimize the nature of the PRC threat.

At the moment, it appears that Beijing has successfully achieved its objectives through ADIZ intimidation. Since 2020, the PRC has moved its pressure campaign from the South China Sea to the Taiwan Strait. The number of aircraft has increased substantially, and Taiwan is regularly surrounded by PLA and PLAN assets. While the international community condemns these actions, and Taiwan has received an increased level of support, this increase in visibility and support has not translated into third parties taking specific actions to slow down or deter PRC military activities around Taiwan. The median line of the Taiwan Strait—a de facto boundary that created some semblance of cross-Strait stability—is no more. Taiwan cannot push back on all fronts against these PRC incursions.

The consistent altering of the status quo in the Taiwan Strait is a troubling development that Washington must address.The 1979 Taiwan Relations Act (TRA)provides a legal rationale for increasing US support for Taiwan in light of the PRC pressure campaign. Section two of the TRA stipulates that it is the policy of the United States “to consider any effort to determine the future of Taiwan by other than peaceful means, including by boycotts or embargoes, a threat to the peace and security of the Western Pacific area and of grave concern to the United States” and “to maintain the capacity of the United States to resist any resort to force or other forms of coercion that would jeopardize the security, or the social or economic system, of the people on Taiwan.”

Considering the TRA and the foreign military financing that Taiwan is eligible for due to provisions in the National Defense Authorization Act for fiscal year 2023, Washington can provide Taiwan up to$2 billion in grant assistanceeach year from 2023 to 2027. One such thing that should take priority is additional radar systems and ground-based missile systems to improve the Taiwanese military’s ability to track PRC aircraft and vessels. After all, a civilian boat was able to transit the Taiwan Strait and crash into a dock in Taipei without being stopped. Providing Taiwan with more mechanisms to track PRC activity will increase the overall situational awareness of such movements. Conversations with Taiwanese officials point to this as a dire need: They do not have enough maritime radar to track everything.

Providing Taiwan with more fuel and spare parts for its current aircraft would also limit the damage to the MND’s budget for intercepting sorties. With the increase in PLAN and CCG activities around Taiwan and its outlying islands, additional support in the maritime domain is necessary. Moreover, more initiatives like the April 2024 naval exercise between the U.S. and Taiwanese navies should become more regular, and the two sides should also conduct similar operations with their coast guards. After all, Washington and Taipei demonstrated that bilateral exercises are possible without causing conflict with Beijing; Washington should then mobilize its regional allies, namely Tokyo and Manila, to join in the coast guard exercises. Japan, Taiwan, and the Philippines all face similar maritime threats from the PRC, so better connectivity and greater trust among all parties benefit the region. The greater contact and interoperability that these three countries have, the better the overall operational picture will be in the event of a worst-case scenario.

It is unrealistic to argue that Taiwan or the United States will be able to stop the PRC aerial and maritime incursions around Taiwan. They have become normalized and are a part of the ever-deteriorating status quo in the Taiwan Strait. With this failure in mind, Washington 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. After all, officials in Taipei quickly acknowledged that this was a war of attrition. Both Taipei and Washington need to start acting like it.

About the authors:

• Thomas J. Shattuck, a Non-Resident Fellow at the Foreign Policy Research Institute, is a Senior Program Manager at the University of Pennsylvania’s Perry World House. He is a 2024-25 non-resident WSD-Handa Fellow at the Pacific Forum and a 2024-25 non-resident Research Fellow at the Modern War Institute at West Point.
• Benjamin Lewis is a co-founder of PLATracker, an organization dedicated to data-driven analysis of the Chinese military and regional security developments in the Indo-Pacific.

Source: This article was published by FPRI

[1] Neither Krach nor Azar responded to requests and outreach for comment.