Are NOTAMs China’s New Airspace Denial Tactic?
On March 27, 2026, a civil aviation authority in Shanghai issued a Notice to Airmen (NOTAM) restricting access to 28,000 square miles of international airspace off the coast of China. The extraordinary duration of the airspace restrictions—40 days—sowed confusion. Unlike previous extended airspace restrictions, the NOTAM did not accompany any major People’s Republic of China (PRC) military exercises, raising questions regarding Beijing’s motives. Nonetheless, the airspace restriction followed a recent pattern of PRC civil aviation authorities employing NOTAMs to close off areas primarily used by foreign military aircraft, rather than commercial planes. The manner in which the airspace restrictions are clearly targeted at foreign military activity suggests that the abuse of NOTAMs is becoming a tool in Beijing’s anti-access/area denial (A2/AD) strategy.
NOTAMs have emerged only recently as a point of contention in the PRC’s foreign policy. Indeed, NOTAMs are usually only relevant to commercial aviation. Issued by states’ air traffic control authorities, they serve to warn commercial pilots of potential aviation hazards, such as inclement weather or upcoming military exercises. International airspace—areas beyond 12 nautical miles of coastlines—is divided across the world into flight information regions (FIRs). Civil aviation authorities from various countries take responsibility for conducting air traffic control over FIRs. However, air traffic control over an FIR is not synonymous with sovereignty. For this reason, International Civil Aviation Organization (ICAO) rules clarify that state aircraft—e.g. military planes—do not need to heed orders from air traffic control in international airspace.
This makes the PRC’s restrictions all the more puzzling. The exclusion zones outlined in the March 27 NOTAM are neatly arranged so as to avoid intersection with any major civil aviation air route in East Asia. Hence the exclusion zones appear as a patchwork of odd shapes. In other words, China’s civil aviation authorities issued restrictions to airspace that commercial aircraft would not access anyway. Indeed, some tourist agencies took the measure of specifically clarifying that the 40-day NOTAM was relevant to military aviation alone and would not affect commercial travel.
Given that the restrictions apply to zones that are frequented by PRC and foreign military aircraft—such as American surveillance planes—it is more likely that the measure is aimed at impeding adversary entry to airspace near China’s coast. The PRC has been particularly opposed to surveillance aircraft nearing its Northern Sea Fleet headquarters in Qingdao, close to the restricted zones. While foreign military aircraft do not need to cooperate with China’s civil aviation authorities, the NOTAMs may compel commanders to conclude that the airspace may not be safe for access, or pressure incoming pilots to self-identify with PRC aviation authorities for safety. Indeed, the NOTAMs, organized during a busy season of U.S. and allied exercises in East Asia, may be intended to deliver the indirect message that “this international airspace is reserved for PRC military use only.”
This is not the first time China has announced a “patchwork” style of airspace restrictions that skirted civil aviation routes. In 2024, Chinese air traffic control issued several NOTAMs restricting oddly shaped stretches of airspace to the north and south of Taiwan for three days. The NOTAMs coincided with large-scale People’s Liberation Army (PLA) exercises around Taiwan. Yet the restricted areas extended to airspace far beyond the Taiwan Strait—and where no PRC drills took place. Indeed, just a few weeks before those exercises, PRC air traffic control had issued additional unexplained NOTAMs restricting enormous stretches of airspace much closer to the Yellow Sea. The measures escaped major attention because the wider context of the activity was not clear. Given that the PRC has now established a pattern of employing large-scale, unexplained restrictions to international airspace near its shores, it is now reasonable to assume that Beijing is seeking to convert air traffic control authority into a kind of provisional “right of denial” to any foreign aircraft, commercial or military.
The PRC has a track record of bending the norms around international airspace to suit its strategic objectives. In 2020, Hong Kong air traffic control blocked a Taiwanese charter plane from resupplying the Taiwan-administered Dongsha Island in the South China Sea. Seven years earlier, in November 2013, Beijing announced a drastic expansion of its air defense identification zone (ADIZ)—the area in which the PRC expects incoming aircraft to identify themselves to aviation authorities or face interception. The PRC’s ADIZ expansion constituted a swathe of airspace in the heart of the East China Sea—encompassing several of the zones restricted by PRC’s NOTAMs in 2024 and 2026. In response to the 2013 ADIZ expansion, the United States, Japan, and South Korea vowed that their military aircraft would not respect the requirement to report entry to Chinese authorities. The recent NOTAM-based restrictions may be a backdoor method of compelling foreign aircraft to announce their entrance into international airspace near China, akin to an ADIZ.
The 2026 airspace restriction elapsed on May 6. The only notable PRC military activity that occurred over that time was the deployment of a naval group through Japan’s Ryukyu Islands in response to Tokyo dispatching a warship through the Taiwan Strait. Major PRC air activity, which could have justified some part of the 40-day airspace restriction, was not reported. Meanwhile, the United States, the Philippines, Japan, and other allies conducted the annual Balikatan combined exercises in the South China Sea. Though some anticipated that the PLA might use some of the airspace reserved in the 40-day NOTAM for its own, reciprocal exercises, it did not.
How did the United States and partners react to this round of international airspace restrictions by China? Though Washington did not issue public statements regarding the airspace closures, this author was able to observe through open source flight tracking software that U.S. Navy P-8 Poseidon surveillance aircraft nonetheless flew several missions in and around the restricted zones. Indeed, even a New Zealand Defense Force Poseidon aircraft was observed one degree in longitude from the restricted zones (approximately 60 miles) before switching off its transponder and disappearing from observation. Open source tracking thus suggests that the United States, and even partner militaries, have not been deterred from accessing international airspace that the PRC has sought to restrict.
However, questions remain regarding whether the PRC is drawing a strategic advantage from its abuse of air traffic control over its FIR. For example, did U.S. and allied aircraft notify PRC aviation authorities when entering the zones restricted by NOTAMs—a measure they would not have taken before the restrictions? An important hypothetical must also be asked: Would the United States and allies refrain from military exercises in areas that have been reserved in advance by the PRC’s aviation authorities? While the location of restricted areas is closer to the coast of China than allied exercises might usually delve, it is conceivable that Beijing is seeking to pre-empt access and establish a norm of “first-come-first served” for access to international airspace during busy seasons of military activity.
It is laudable that the U.S. military aircraft continued regular patrol missions in East Asia, in spite of PRC aviation restrictions. In 2024, during the PRC’s December exercises accompanying NOTAMs, this author did not observe U.S. aircraft entering restricted airspace with transponders switched on. In addition to the U.S. military’s telegraphed attempts to flout the restrictions, the Pentagon should publicly announce that it will not heed NOTAMs alone when deciding where to plan exercises or freedom of navigation missions. Clear signaling, especially at this earlier stage of status quo revision, will prevent NOTAM abuse from becoming a proven method in the PRC’s grey zone toolbox.
Benjamin Sando is a research fellow at the Global Taiwan Institut.
The author would like to thank Global Taiwan Institute intern Eliza Cormier with her help with the research for this article.