On November 28, Taiwan’s Ministry of National Defense announced that the People’s Liberation Army Air Force (PLAAF) and Navy (PLAN) began conducting joint combat readiness patrols in Taiwan’s northern, southwestern, and eastern airspace at 6:20 p.m. that night.
The Chinese military’s incursions into Taiwan’s air defense identification zone (ADIZ) have attracted significant attention, mainly focusing on the sorties reported daily in Taiwan’s Ministry of National Defense press releases and their political implications. However, the joint combat readiness patrols and their military implications have long been overlooked. These patrols pose a greater threat to Taiwan than the typical daily incursions and are more significant for analysis. In fact, the recent emerging trends have even more important strategic implications.
Based on the press release from Taiwan’s Ministry of National Defense, the current level of PLAN and PLAAF incursions into Taiwan’s ADIZ appears to have reached a plateau, as joint combat readiness patrols and daily incursions did not significantly increase compared to previous years. Despite China’s rising military expenditures, which could logically lead to more frequent incursions, this situation may suggest that the PLA’s current operational capacity has reached its maximum. Still, the intensity of incursions could increase with further strengthening of logistical capabilities and expansion of the PLAN and PLAAF’s structure.
Trends of Joint Combat Readiness Patrols
Although some analyses suggest that China’s air and naval incursions against Taiwan have become more intense since President Lai Ching-te’s inauguration in May, the situation regarding joint combat readiness patrols (a highly threatening mission to Taiwan) this year presents a more complex pattern.
According to official Chinese statements, the joint combat readiness patrols are meant to assess the integrated operations capabilities of multiple military branches. The preparations before the exercise are equivalent to combat readiness, and the exercise itself is considered to be in a combat state. Chinese scholars have also pointed out that during the readiness patrols, the PLA’s equipment and personnel are in a complete combat state, ready to respond to any accidental conflicts or external attacks. According to Taiwan’s Ministry of National Defense press release, the term “joint” at the very least refers to the involvement of both the PLAAF and PLAN in the “combat readiness patrols.”
The Chinese Ministry of Defense announced on August 10, 2022, that it would conduct regular combat readiness patrols around Taiwan. Taiwan’s Ministry of National Defense began releasing information on the PLA’s joint combat readiness patrols against Taiwan around June 2023. A comparison of the period from June to November in 2023 and 2024 reveals several notable trends.
Table 1 below compares the situations in 2023 and 2024. It is important to note that the numbers of military aircraft and ships are based on the figures released by Taiwan’s Ministry of National Defense the day after the patrols, reflecting the activities of the PLAN and PLAAF on the specific days when joint combat readiness patrols took place. The reason for using this data instead of the figures released in the initial Ministry of National Defense press releases on joint combat readiness patrols is that these press releases are typically issued 2-3 hours after the patrols begin. By that time, the patrols are often still ongoing, so they may not include all the sorties and activities.
Furthermore, if the PLA conducts joint combat readiness patrols on a given day, the Eastern Theater Command would inevitably coordinate and manage the forces in Taiwan’s surrounding air and sea areas to some extent. As a result, the naval and air forces present around Taiwan could also be considered part of the joint combat readiness patrol, such as those serving as reserve units or simulated enemy forces.
In addition, the average proportion of PLA aircraft crossing the median line was 51.9 percent in June-November 2023, which rose to 73 percent for the same period of 2024. (Note: this ratio is the average of each individual aircraft’s data, rather than the ratio of “average sorties of PLA aircraft per patrol” to “average sorties of PLA aircraft crossing the median line per patrol” in the chart above.)
The following trends can be observed from the data above. First, the number of joint combat readiness patrols actually decreased, and the average number of PLA and PLAAF assets involved did not increase significantly. The average number of PLA aircraft per patrol decreased slightly, while the average number of PLA ships per patrol has slightly increased, by one vessel.
However, the average number of PLA aircraft crossing the median line per patrol significantly increased, rising by 6.2 sorties. Finally, the proportion of PLA aircraft crossing the median line significantly increased, by an average of approximately 21 percentage points.
The trends above have two implications. The number of joint combat readiness patrols has decreased. This suggests that the PLA’s planning and resources for real combat drills and exercises, such as joint combat readiness patrols, are likely limited and fixed. Given that two Joint Sword exercises were conducted in 2024, consuming considerable resources and increasing logistical and maintenance burdens, the frequency of joint combat readiness patrols has consequently decreased.
Second, the PLA has essentially increased the intensity of its incursions into Taiwan while keeping the number of sorties and operational maintenance costs relatively unchanged. The PLA may be intending to conduct higher-intensity readiness exercises against Taiwan or perhaps has been ordered to apply greater pressure through incursions. However, this has been achieved without a significant increase in the number of sorties or operational costs. Instead, the PLA has increased the proportion of aircraft crossing the Taiwan Strait median line (i.e., getting closer to Taiwan) while maintaining a similar total number of sorties.
This implication can also be further verified by observing the daily incursions of the PLAN and PLAAF into Taiwan’s airspace. The charts below show the trends in daily incursions by China’s military into Taiwan’s ADIZ during similar periods in 2022, 2023, and 2024
First, the average daily sorties in 2024 have not significantly increased compared to the past two years. It is important to note that January 13, 2024, was Taiwan’s presidential election day, so China may have reduced its incursions to some extent to avoid generating anti-China sentiment before the election, especially in the second half of 2023.
Second, the average daily sorties of PLA aircraft crossing the median line, the average daily proportion of PLA aircraft crossing the median line, and the average daily number of PLA ships have indeed increased.
Nighttime Joint Combat Readiness Patrols
One aspect of the joint combat readiness patrols that warrants further analysis are the PLA’s nighttime missions. The table below presents the currently available data on nighttime combat readiness patrols.
According to Taiwan’s Ministry of National Defense press releases, the PLA has conducted nighttime joint combat readiness patrols seven times from June 2023 to the present. The timing and sorties of these nighttime missions reveal the following trends: First, nighttime combat readiness patrols do not follow a clear pattern. Second, the start times of the nighttime combat readiness patrols are not fixed. Third, during the large-scale theater-level drills and exercises conducted by the PLA in September and October of 2023 and 2024, no nighttime combat readiness patrols were carried out.
This suggests that nighttime joint combat readiness patrols may not yet be a fixed exercise subject, so their timing does not follow a clear pattern. Additionally, during large-scale theater-level drills and exercises, nighttime combat readiness patrols are temporarily suspended. This also implies that once the Eastern Theater Command institutionalizes nighttime joint combat readiness patrols, Taiwan will likely face more frequent incursions of nighttime joint combat readiness patrols.
Policy Implications
From the trends above, it can be observed that the current level of PLAN and PLAAF incursions into Taiwan’s ADIZ appears to have reached a certain limit. Whether it is joint combat readiness patrols or daily incursions into Taiwan’s ADIZ, the PLA’s activities from June to November 2024 have not significantly increased compared to the same period in previous years. Interestingly, this situation occurs against the backdrop of increasing military expenditures for the PLA, which would logically lead to a higher frequency and total number of incursions near Taiwan (China’s top priority target). Whether for military readiness or escalating intimidation against Taiwan, the PLA or Eastern Theater Command would likely have a high chance of success in securing more resources.
One possible reason is that the PLAN and PLAAF’s capability for operations around Taiwan have reached a certain bottleneck. On one hand, the PLA may be constrained by logistical support for aircraft and ships, as well as personnel rotations, which has prevented an expansion of daily incursions into Taiwan’s ADIZ. On the other hand, the fact that nighttime joint combat readiness patrols have not been institutionalized indicates that the PLA’s nighttime joint operational capabilities may still be limited. The solution to the former is to strengthen logistical support and expand the force size, while the latter requires enhanced training to improve nighttime combat readiness.
However, the PLA may still adjust its sortie planning to flexibly increase its incursions into Taiwan. Over the past six months of joint combat readiness patrols, an average of only 23 aircraft, or 73 percent of the total sorties, crossed the Taiwan Strait median line. Even under the current conditions, where the PLA’s logistical capacity and combat readiness have not significantly changed, it can still increase the proportion of aircraft crossing the Taiwan Strait median line to create greater incursions and pressure on Taiwan. For example, in 2024, at least 16 instances were recorded in which the PLAAF aircraft detected by Taiwan all crossed the Taiwan Strait median line during ADIZ incursions. The only question is whether the PLA is willing to escalate in this manner.
If the PLAN and PLAAF’s capacity and force size around Taiwan increase in the future, it is likely that the frequency of joint combat readiness patrols, both day and night, will exceed the current average of once per week, with the number of naval and air forces also potentially increasing.