STRATDELA Special Issue #3: ADIZ 101

This week we’ve seen yet another joint patrol by Russian and Chinese heavy bombers over East China Sea and Sea of Japan.

Everything was relatively calm, and footage of Bears landing in China is quite something, but now everyone once again remembered about ADIZ — Air Defense Identification Zones. ADIZ established by the Republic of Korea was, well, penetrated, and it is a good time to write something about such things in general.

In formal terms, ADIZ is a specially designated portion of airspace of defined dimensions, within which aircraft must comply with special procedures (although voluntarily established as well) for identification and/or reporting other than those related to the provision of air traffic services (ATSS).

First such zones were established jointly by the U.S. and Canada in 1950–1951 to counter Soviet strategic bombers. Air defence identification zones have now been established in at least 25 countries. In 9 states (Argentina, Brazil, Finland, Libya, Peru, Poland, Sri Lanka, Turkey and Uruguay), the air defence identification zone covers exclusively a country’s sovereign airspace.

In another 16 mostly maritime states (Bangladesh, Canada, China, Cuba, Iceland, India, Indonesia, Iran, Japan, Republic of Korea, Myanmar, the Philippines, Pakistan, Panama and Thailand) the zone, while for others it extends far beyond.

At the same time, from an international law perspective, the principles regulating international aviation outside national airspace are governed by the Chicago Convention on International Civil Aviation adopted in 1947.

The implementation and development of the rules of international civil aviation under the Chicago Convention is regulated by ICAO (International Civil Aviation Organization). According to the convention, the possibility of establishing ADIZ may derive from sovereignty over national airspace. On the other hand, any coercive inducements related to the implementation of ADIZ can only be applied within this very same sovereign airspace.

Separately, a distinction should be made between the concepts of ADIZ and Flight Information Regions (FIR). Flight Information Regions define the areas of responsibility of state air traffic control services in the field of air traffic management, safety and efficiency of civil aviation flights. The boundaries of such areas are agreed and approved at ICAO international conventions.

Implementation of the ADIZ regime outside national airspace is possible with the voluntary cooperation of the aircraft crew (including under threat of denial of access to national airspace) or by various means of active or passive identification (using radar detection equipment or visual target identification by the interceptor and fighter jets). The most ‘active’ situation with ADIZ remains in the East Asia.

One of the most contested ADIZ was established by Taiwan in the 1950s (“TADIZ”), following the lead by ROK and Japan in 1951. In fact, these ADIZ were actually established by the U.S. military during the Korean War, during undeclared military conflicts with the People’s Republic of China supported by the Soviet Union and during the First and Second Taiwan Strait Crises of 1954–1955 and 1958 respectively.

In the 1960s and 1970s, the TADIZ zone was maintained jointly by the armed forces of the US and the Republic of China. After that, under the terms of the 1954 Sino-American Treaty on Mutual Defense, U.S. security guarantees covered exclusively the island of Taiwan and the nearby Pescadero Archipelago, implementation of the western part of the TADIZ zone was carried out exclusively by the forces of the Kuomintang government.

The command of the U.S. Air Force stationed on the island of Taiwan drew the “median line” of the Taiwan Strait, nicknamed the Davis Line. This line informally set the western limit of U.S. military aviation activity to avoid unintended collisions and other incidents. However, in much of the waters of the Taiwan Strait, the Median Line has shifted towards the coast of mainland China.

After the normalisation of bilateral relations between China and the U.S. in 1979, the mutual defence pact was abrogated, the U.S. withdrew its military bases from the island and as a symbolic gesture stopped “officially recognising” the western part of Taiwan’s air defence identification zone located beyond the Davis Line. On the other hand, in practice U.S. diplomacy succeeded in getting the Chinese side to agree to limit its military activities to the Davis Line.

During the period of relative technical backwardness of PLA Air Force this tacit agreement was implemented up to the early 2000s and even successfully survived the Third Taiwan Strait Crisis of 1996. However, since the 2000s, China has become aware of its growing military capabilities and its disgruntlement over the rise of separatist sentiment in Taiwan. Meanwhile, the sorties in the eastern part of the TADIZ zone remained isolated and exceptional throughout the 2000s and were seen as a political signal of China’s dissatisfaction with the current state of bilateral relations “between the straits”.

Since 2019, however, the military presence of PRC aircraft in areas east of the “median line” has become a constant phenomenon. The daily number of sorties can range from 4–6 per day, in small groups of combat and special aircraft. During the escalation of relations, for example in October 2021 or August 2022, the scale of military activity increases by an order of magnitude — up to 40–50 sorties daily. The air build-up is mainly carried out by strike and fighter aircraft, while the special aviation — ASW, ECM, ISR, AEW and AWACS aircraft continue to operate as part of pre-planned activities.

Why does PLA engage in such activities? Well, it seems, by sending warplanes into the TADIZ zone, the PRC’s political leadership is pursuing a set of diverse goals. Firstly, of course — the activity in the eastern part of the Taiwan Strait serves as a political signal of China’s determination to use force to protect the One China principle.

Second, the PLA has to increase its activity in the region in order to prepare for a possible military operation against Taiwan. On the one hand, these sorties are intended to fulfill various military missions (suppressing air defense, air superiority, strikes against military and political infrastructure of the island). On the other hand, military activity involves a variety of reconnaissance missions: in particular, assessing the response of Taiwan’s air force, identifying air defense positions, studying the capabilities of Taiwan’s radars, etc. Also, it can be argued that the constant need for fighter sorties to identify aircraft intruding TADIZ places a serious burden on the Air Force of Taiwan and could significantly affect the technical state of the aircraft and, consequently, its combat readiness.

Third, the growing military activity in the TADIZ zone addresses the rather applied political objective of taking control of the airspace in the western part of the Taiwan Strait. In 2018, the PRC Civil Aviation Administration announced the expansion of the M503 air corridor to serve the cities of Xiamen, Fuzhou and Dongshan. This air corridor is located near the southeastern border of the Shanghai Flight Information District and was commissioned to strengthen transport connectivity along the Fujian coast and reduce pressure on existing corridors between Shanghai and Hong Kong. As the M503 corridor runs east of the Jinmen and Matsu archipelagos, which are still under Taiwanese control, this creates obvious political friction.

To sum up, the problems associated with the implementation of the ADIZ zone are most acute in the context of the Taiwan crisis. Intense maneuvers by military aircraft in airspace with an uncertain status under international law mean increased risks of a variety of dangerous incidents that could lead to uncontrolled military escalation in the region.

Back to bombers. Russian Long-Range Aviation (as well as heavy ASW patrol aircraft) have been flying towards CONUS for ages, and while there is a routine notification mechanism, photo ops are quite regular.

As for the Korean ADIZ, Moscow and Seoul signed a defense cooperation agreement some time ago, and there are rumors that it includes an obligation of prior notifications — which are seemingly ignored by the Russian side, according to Korean statements. If that is true, this means that, well, formal risk reduction mechanisms are not always working as planned. However, it is crucial to emphasize that ADIZ itself can be considered quite an escalatory move, especially once those overlap and the overall political-military situation becomes inflammable.

Basically, those can be seen from Moscow and Beijing as a tool to test the redlines and add pressure once needed. So, a pressure leads to counterpressure, and that’s how escalation works. What can we do with such a sad dynamic? Well, my suggestion remains the same: talk, exchange concerns, acknowledge and address those concerns — and try to find a way out of the downward spiral of the history textbook we all live in.