Scenarios of China’s South China Sea ADIZ and the consequences

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Scenarios of Chinas South China Sea ADIZ and the consequencesEven though numerous countries around the world have unilaterally established the Air Defense Identification Zone (ADIZ) since the 1950s to control a specific range of their airspace intentionally, thus far, there is no international legal instrument to govern this issue explicitly. Generally, the establishment of ADIZ is understood as a way to allow States enough time to prepare for a potential air attack. Within such an area, foreign aircraft must comply with States’ requirements for identification, including submitting flight plans, maintaining two-way radio communication, operating the secondary radar transponder, and so forth. ADIZs are usually established in the national airspace adjacent to other nations’ sovereign airspace, like China’s ADIZ which was created above the Senkaku archipelago in 2013 – a disputed area on the East China Sea between China and Japan.

Since the beginning of 2020, due to China's increasingly unruly acts in the South China Sea (SCS), there have been speculations on the possibility of an ADIZ by Beijing above this sea area. Furthermore, there are also numerous questions concerning the scenario China will follow in case it creates such ADIZ. Many SCS experts have considered this issue carefully and believe that there are three possible scenarios:

In the first scenario, an ADIZ will be created above the Paracel Islands. This scenario is grounded in the fact that in 1996, China declared its archipelagic baselines surrounding the Paracel Islands. Besides, it is laid down that China’s EEZ and continental shelf “extend to a distance of 200 nm from the baselines” under Article 2 of China’s Exclusive Economic Zone (EEZ) and Continental Shelf Act 1998. Pursuant to this legal document, the area within the distance of 200 nm surrounding the Paracel Islands belongs to China’s EEZ and continental shelf. Therefore, if China establishes an ADIZ above the Paracel Islands, its range may not only cover the airspace above Beijing’s claimed 12 nm territorial sea around the Islands but also extend further to cover the airspace above its claimed EEZ and continental shelf surrounding the Paracel Islands. Such ADIZ will probably overlap not only the airspaces above the EEZs and continental shelf of Vietnam but also those of the Philippines. Not to mention, it may also overlap the Flight Information Region (FIR) of Ho Chi Minh, Manila, as well as other cities.

 In 2009, China’s Permanent Mission to the United Nations (UN) submitted the Note Verbale CML/17/2009 in which it once again asserted its “sovereignty” over the Paracel Islands. Accordingly, China claimed that “China has indisputable sovereignty over the islands in the South China Sea and the adjacent waters.” Such repeated sovereignty claim makes China seem to have “every reason” to establish the ADIZ above the Paracel Islands because (1): As Beijing declared the baselines surrounding the islands, it would not be a problem to establish an ADIZ in the airspace beyond the Paracel Islands territorial sea. (2) A Chinese durable airport was built on Woody Island of the Paracel Islands to guarantee military activities once Beijing enforces an ADIZ (3) More importantly, the Paracel Islands is the subject in a bilateral dispute between China and Vietnam, with Vietnam being the sole country claiming sovereignty over the islands.

Given the above analysis, from a legal perspective, the establishment of China's SCS ADIZ is most likely to take place in the airspace of the Paracel Islands. Even the United States - China Economic and Security Review Commission has recently speculated that Beijing would establish ADIZs in both Paracel and Spratly Islands, with the establishment of the ADIZ covering the Paracel Islands and adjacent water being the priority, followed by the second ADIZ over the Spratly Islands when their military capability is sufficiently enhanced. In the second scenario, the ADIZ will be created above the Spratly Islands. The sovereignty dispute in the Spratly Islands is among five states – six parties (including Vietnam, Brunei, China, Malaysia, Philippines, and Taiwan); thus, China may set up an ADIZ here to consolidate its “sovereignty” claims. In its Note Verbal No. CML/8/2011 submitted to the UN, Beijing asserted that the establishment of Spratly ADIZ would enable China to reaffirm the viewpoint mentioned above. Nevertheless, Beijing would still have to weigh up pros and cons prior to the establishment of such ADIZ for three reasons: (1) It may overlap FIRs of Ho Chi Minh, Manila, Singapore and Kota Kinabalu (Malaysia), thus leading to condemnations from Vietnam, the Philippines, Singapore, and Malaysia; (2) Because the sovereignty dispute over the Spratly Islands involves multiple parties, China may have to cope with all parties’ reactions if it creates an ADIZ over this airspace; (3) Given that the Spratly Islands are located in a strategic area of international navigation and aviation, China’s ADIZ is prone to severe criticisms by regional states and other stakeholders like the US, Japan, Australia, and even Russia.

There is also a technical issue regarding the establishment of SCS ADIZ. In order to provide the exact coordinates of ADIZ, China must make a territorial claim in the waters of the Spratly Islands or of a feature belonging to the islands. Nevertheless, such claim may lead to another fierce debate, given the severe criticisms towards China’s recent reclamation and construction work on the features in the Spratly Islands. Moreover, the US Navy has repeatedly deployed destroyers into the area within the 12 nm of China’s claimed features in the archipelago. Despite the objections from Beijing, the US Department of State declared that the deployment aimed at demonstrating the freedom of navigation in international water. On the other hand, the deployment of US destroyers in the SCS also challenged China's sovereignty claims over the features that it illegally occupied, reclaimed, and constructed in the Spratly Islands.

Hence, China must take this into account before establishing ADIZ over Spratly Islands because this action would bring nothing but a negative impact on China’s national interest in the region. Additionally, the ADIZ contradicts China’s regular statement that the situation in SCS is stable, in overall, there will be no potential major conflicts, and after conducting land reclamation, China will not militarize the Spratly Islands but merely invest in “major facilities” for “mutual peaceful development,” such as search and rescue, maritime scientific research, and so forth.

In the third scenario, the ADIZ will be created above the “nine-dash line.” In Note Verbale No. CML/17/2009 dated 7th May 2009, China officially promulgated its “sovereignty” claim over the “nine-dash line” in the SCS, which could be considered as the foundation for China’s potential SCS ADIZs. Nevertheless, the ADIZ above the nine-dash line does not seem to be appropriate since this line itself remains vague, with no legal and historical basis as well as exact geographical coordinates. Once China promulgates the nine-dash line ADIZ, it will have to provide the exact geographic coordinates for foreign aircraft to comply with its identification rules. Accordingly, the ADIZ above the “nine-dash line” needs to demonstrate the precise location of the line, which contradicts China’s “nine-dash line” claim. In accordance with the “nine-dash line” map attached to Note Verbal no. CML/17/2009, a potential ADIZ above the line may overlap the FIRs of Ho Chi Minh, Hanoi, Hong Kong, Manila, Singapore, and Kota Kinabalu. Thus, just akin to the above-mentioned ADIZ over Spratly Island, the ADIZ over “nine-dash line” will be confronted by the criticisms from the parties who are responsible for operating SCS FIRs.

Of the three scenarios above, an ADIZ will be most likely established in the Paracel Islands. Although Beijing seems ready to announce the establishment and enforcement of an ADIZ in the SCS, it still needs to weigh up the pros and cons.

Due to the strategic location of the SCS and the nature of the disputes in this region, scenarios for China’s potential SCS ADIZ may lead to the escalation of tensions among China and other countries, first and foremost in the diplomatic and legal perspective, just like those that occurred when China created an ADIZ over the East China Sea, specifically:

On the diplomatic aspect, there are complex disputes regarding the sovereignty over maritime features in the SCS, as well as other maritime issues concerning the application of the UNCLOS 1982. Once China establishes the SCS ADIZs, all stakeholders will instantly accuse China of escalating the dispute and altering the status quo of the SCS in both bilateral and multilateral forums. Any country seeking to control this area completely can expect challenges from others. In case China implements the identification rules in the SCS, which are similar to those in the East China Sea ADIZ, they will be vehemently opposed by countries having aviation and navigational interests in the area such as the US, or those operating FIRs in this area, such as Singapore and Indonesia.

On the legal aspect, the ruling of the Permanent Court of Arbitration (PCA) in 2016 emphasized that despite China’s non-recognition of the Tribunal's awards and non-participation in the arbitral proceedings, it remains a party of a case filed by the Philippines and is thus legally bound by the decisions. Therefore, in case China creates an ADIZ in the airspace of either the Spratly Islands or the “nine-dash line”, the Philippines may request the PCA to announce measures concerning this ADIZ under Article 290, Section 1 of the UNCLOS 1982. Against this backdrop, Manila could argue that such ADIZ impedes the Philippines’ normal aviation activities in the airspace above its EEZ and continental shelf, leading to irreparable economic losses. This argument is likely to fulfil the condition laid down by the International Tribunal for the Law of the Sea (ITLOS) to render provisional measures, which is akin to measures prescribed by ITLOS in M/V Louisa case (Saint Vincent and the Grenadines v. the Kingdom of Spain). Therefore, the above argument may become the legal foundation for the Philippines to request the PCA for the provisional measures to deter China from enforcing the ADIZs over the SCS, while waiting for the final awards of the Tribunal. Similar to the Philippines, the other parties of the SCS disputes may also initiate the arbitral proceedings under Annex VII of the UNCLOS 1982 against China’s SCS ADIZs, in accordance with Article 58 and 87 of the UNCLOS 1982. The claimants may concomitantly request ITLOS to adopt provisional measures pursuant to Article 290, Section 5 of the UNCLOS 1982, pending the PCA’s decision.

Notably, due to the SCS strategic role and geographical location, its stability is an inseparable part of the national interests of several countries within or beyond the region. Thus, every aggressive action in this area, such as the imposition of an ADIZ, may encounter either legal or diplomatic challenges.

To date, international law hardly provides any legal foundation for states to either establish or maintain ADIZs. Currently, international law experts still adopt two contradictory views towards this issue. While some advocates argue that international law allows states to set up ADIZs, the oppositions do not accept any legal foundation for such claims. In practice, nevertheless, many countries have unilaterally established ADIZs since the 1950s, and only a limited number of such ADIZs have been condemned by other countries or the international community. The ADIZ that China declared to establish in the East China Sea in late 2013 “triggered” diplomatic conflicts among parties. It also raised questions on the legal foundation of ADIZs created in disputed areas that overlap other nations' FIRs. States are concerned about the potential establishment of China’s SCS ADIZs since it may lead to a critical escalation of political conflict in the region.