Why are tensions escalating in the South China Sea?

di Alessandra Palmeri - 30 Settembre 2020

  from Lisbon, Portugal

   DOI: 10.48256/TDM2012_00129


The South China Sea is a contested sea of the Western Pacific Ocean. It is a critical commercial gateway for a significant portion of the world’s merchant shipping, and hence it represents an important economic and strategic sub-region of the Indo Pacific. It is also the site of several complex territorial disputes.

Geographically, it plays a significant role in the geopolitics of the Indo-Pacific.

The South China Sea is bordered by Brunei, Cambodia, China, Indonesia, Malaysia, The Philippines, Singapore, Taiwan, Thailand and Vietnam. Their recent economic growth has contributed to a large portion of the world’s commercial merchant shipping passing through these waters. Japan and South Korea rely heavily on the South China Sea for their supply of fuels and raw materials as an export route. (2020, Lowy Institute.)

The South China Sea also contains rich, though unregulated and over-exploited fishing grounds and is reported to hold significant reserves of undiscovered oil and gas, which is an aggravating factor in maritime and territorial disputes. The major Islands and reef formations in the South China Sea are the Spratly Islands, Paracel Islands, Pratas, the Natuna Islands and Scarborough Shoal (Ibid). It encompasses roughly 3.625 million sq. About half of the Islands are located within 370 km or 200 nautical miles of Vietnam, whereas all of them are within 370 km of China’s Hainan Island. 

Origin of the nine-dashed lines 

China’s current borders largely came out during the Manchu dynasty in the 18th century and were reinforced after the signing of the Treaty of Westphalia in 1648. China argues that the territory and islands to which it lays claim in the South China Sea were incorporated into China during the Manchu dynasty and that the territory was labelled as Chinese on historical documents and maps, giving China a historical claim to these regions. 

The nine-dashed line first appeared on Chinese maps in 1947 when the Kuomintang government ruled by Chiang Kai-Shek drew an eleven-dashed line around the sea and around the islands that Beijing claims are under its sovereignty. When the Chinese Communist Party gained control of China, they kept the line but changed it into nine dashes instead of eleven dashes. (2015, Broderick K.)

History of territorial disputes in the South China Sea

The territorial disputes in the South China Sea have a long history and the countries mainly involved were: Japan, Vietnam (including the Soviet Union and American’ presence in 1974), Philippines and Malaysia. 

During World War II, The Japanese Empire used the Islands in the region for various military purposes and asserted that the Islands were not claimed by anyone when the Imperial Japanese Navy took control of them. 

After the war, Imperial Japan had to relinquish control of the Islands with the Treaty of San Francisco in 1951. (Chung Chris, 2016)

The Geneva Accords of 1954, which ended the First Indochina War, gave South Vietnam control of the Vietnamese territories, including the islands in the Paracels and Spratlys. Two years later the North Vietnamese government claimed that the People’s Republic of China is the lawful claimant of the islands, while South Vietnam took control of the Paracel Islands. (Nguyen, H., 2020)

After the victory of North Vietnam in the Vietnam War, the PRC (People’s Republic of China) wanted to prevent their occupation of Paracel islands, especially because North Vietnam was an ally of the Soviet Union at that time. 

The PRC’s entrance into the territory

In the latter half of the 1970s, the Philippines and Malaysia started reclaiming the Spratly islands as their own territory. President of the Philippines Ferdinand Marcos (1965–1972), issued Presidential decree no° 1596, declaring the north-western part of the Spratly Islands as Philippine territory. 

In 1988, PRC and Vietnam fought each other near the Johnson Reef, where China received the permission form from the Intergovernmental Oceanographic Commission, to build five observation posts. And later, in 1994, the PRC occupied Mischief Reef which marked the first military confrontation with the Philippine, an ally of the United States. (Koo, Min Gyo 2009)

The occupation and/or control of most parts of the Spratly and Paracel islands has not changed significantly since the middle of 1990s. The PRC controls all of the features in the Paracels. In the Spratlys, Vietnam controls the greatest number of features, while the Philippines has control of eight features, Malaysia five, the PRC five, and the Republic of China one. Balance of power in the Spratlys has greatly shifted since 2013 when the PRC started its island-building activities in the region. (Asia Maritime Transparency Initiative)

Reclamation program of 2013

From the beginning of the 1970s, as part of the Cabbage strategy, China ensured the islands in the nine-dash lines within its control. (Affairs and Current Affairs February 2020)

The Cabbage Strategy is designed to occupy a larger Maritime zone for a particular nation, to gain exclusive national rights over certain bodies of water. The strategy involves building large amounts of man-made Islands in the middle of a large portion of water, building them up until they have enough landmass to claim a local sea under the UN’s “Law of the Sea”. (Liberapedia. 2020. Cabbage Strategy)

In 2013, the largest bilateral/regional issue reached an international dimension when the Philippines approached the Permanent Court of Arbitration to contest the territorial claims in the nine-dash line. In July 2016, the Hague-based PCA ruled that there was no legal basis for China to claim rights over the South China Sea. 

It was pointed out that China’s claims over the resources in the region are incompatible with the exclusive economic zones (EEZs) provided in the United Nations Convention on the Law of the Sea (UNCLOS). The PCA has also concluded that China has violated the Philippines’ sovereign rights and also caused severe harm to the coral reef environment by building artificial islands in the region. 

The parameters defined by UNCLOS

According to the Convention, EEZs were created to give coastal states greater control over the resources within 200 nautical miles of their coastlines. Article 56 of UNCLOS gives states sovereign rights to explore, exploit, conserving and managing the natural resources of the zone. The state also has limited jurisdiction concerning the establishment, use, and preservation of artificial islands, installations, structures and marine scientific research. Article 56 does not allow a state to have exclusive rights to survey or conduct military or reconnaissance missions within its EEZ. (Ben Dolven, Jennifer K. Elsea, Susan V. Lawrence 2015)

International law, as embodied in UNCLOS, governs the rights of states for maritime zones, which are defined in terms of proximity to a coastal state. UNCLOS recognizes that coastal states may claim maritime zones in which they may exercise certain rights: 


Military Implication

China’s land reclamation efforts in the South China Sea could improve China’s ability to maintain ship and aircraft operations in the region on a day-to-day basis, and to conduct combat operations in the region if it were to be the case. 

China could use one or more of the land reclamation sites as refuelling, resupply, and crew rest locations for fishing boats, coast guard cutters, and navy ships that are based in China’s Hainan Island or along China’s mainland coast. 

Besides, small numbers of boats, cutters, and ships might be stationed at one or more of the reclamation sites, perhaps on a rotational basis. Radars and aircraft (including unmanned aerial vehicles [UAVs]) stationed at these sites could increase China’s ability to maintain maritime domain awareness (MDA) over surrounding waters and airspace. (Ben Dolven, Jennifer K. Elsea, Susan V. Lawrence 2015)

Therefore, facilities at the reclamation sites could permit China to maintain a more frequent, more frequent and effective, and operationally effective presence of fishing boats, coast guard ships, and navy ships in the region. 

If China at some point were to declare an air defence identification zone (ADIZ) over the South China Sea, one or more of these sites could be used to support the administration of that ADIZ. (Ibid).

The militarization of the South China Sea

 One of the indicators that an ADIZ zone could be declared soon is the appearance of  KJ500a third-generation airborne early warning and control (AEW&C) aircraft built by Shaanxi Aircraft Corporation.  The aeroplane is earmarked to provide early radar warnings to combat troops to give them an edge in potential future battles and it is capable of tracking nearly 100 vehicles at once. 

Analysis of satellite imagery of existing Chinese military facilities on islands in the South China Sea indicates that these facilities typically feature some combination of the following:

For China, enhancing military facilities in the Spratlys could mitigate the logistical challenges of sustaining operations of navy ships, coast guard cutters, and fishing boats in the southern South China Sea, far from Hainan Island and China’s mainland coast. At present, PLA Navy and China Coast Guard (CCG) vessels operating in the South China Sea must return to bases along the Chinese coast to resupply, conduct major repairs, and give sailors shore leave. (Ibid) 

China’s geopolitical objectives

The South China Sea comprises the Chinese version of the American Caribbean (Spykman, 1942; Kaplan, 2014). 

As Mahon (1890) stated, the United States needed to secure its near seas, so must China and hence its focus on the South China Sea. The Paracels and Spratly Islands offer platforms from which the Chinese Navy/Coast Guard can by sheer presence exert control or varying degrees of coercion throughout the South China Sea. 

The installation of surface-to-air missiles in February 2016, along with J-11 fighters (modified Russian SU-27 Flankers) in late 2015 on Woody Island within the Paracels, illustrates this point (Thayer, 2016).

As the Panama Canal formed and continues to function as a strategic lynchpin for American control, so too does the Strait of Malacca through which transits over 80% of all the crude oil from the Middle East destined for East Asian ports (Haddick, 2014). 

China’s ability to contest existent American control over Malacca serves three objectives:

Firstly, it secures China’s sea lines of communication and trade at crucial points within the Eurasian maritime periphery that links the Indian Ocean basin including the Persian Gulf to the Pacific. Despite two Asian pipelines, China imports 85% of its crude oil through the Strait of Malacca (U.S. Defense Dept. 2015). 

Secondly, it adds insecurity to rival Japan, which also imports nearly all its oil through the Strait of Malacca. Finally, it tangibly reasserts China’s role at the top of a far eastern Asian hierarchy.

China-America dispute in the south China Sea

The United States’ ability to project force into the South China Sea stems from the Seventh Fleet’s home base at Yokosuka, Japan and Kadena Air Force base located on Okinawa. Additional U.S. Marine Corps ground forces and air units are also stationed on Okinawa, roughly 2,040 km (1,100 n.m.) northeast of the South China Sea. 

Meanwhile, 1,700 NM east of the South China Sea, the United States possesses an enormous Air Force base on Guam. While the Marine Corps basing arrangement on Okinawa remains locally controversial, Guam comprises U.S. sovereign territory and sits squarely in the second island chain. Upheld by the Philippine Supreme Court in 2016, a ten-year U.S.- Philippine security agreement comprises another scenario that has yet to completely manifest itself. 

This agreement allows the U.S. to rotate air and naval units temporarily in the Philippines and envisions at least a partial re-opening of Subic Bay and adjacent Clark Field (Figure 2) (Hernandez & Whaley, 2016). A U.S. Navy logistics base in Singapore, near the Strait of Malacca, completes U.S. presence.

Michael Pompeo in July 2020 stated: “The United States champions a free and open Indo-Pacific. Today we are strengthening U.S. policy in a vital, contentious part of that region — the South China Sea. We are making clear: Beijing’s claims to offshore resources across most of the South China Sea are completely unlawful, as is its campaign of bullying to control them. 

The world will not allow Beijing to treat the South China Sea as its maritime empire. America stands with our Southeast Asian allies and partners in protecting their sovereign rights to offshore resources, consistent with their rights and obligations under international law. We stand with the international community in defence of freedom of the seas and respect for sovereignty and reject any push to impose “might makes right” in the South China Sea or the wider region” (United States Department of State, 2020).



The United States, which maintains important interests in ensuring freedom of navigation and securing sea lines of communication (SLOCs), has expressed support for an agreement on a binding code of conduct and other confidence-building measures. China’s claims threaten SLOCs, which are important maritime passages that facilitate trade and the movement of naval forces.

Washington’s defence treaty with Manila could draw the United States into a potential China-Philippines conflict over the substantial natural gas deposits or lucrative fishing grounds in the disputed territory.

The failure of Chinese and Southeast Asian leaders to resolve the disputes by diplomatic means could also undermine international laws governing maritime disputes and encourage destabilizing arms buildups.

In response to Michael Pompeo by a statement posted on Twitter, the Chinese embassy in Washington DC said the US State department “deliberately distorts the facts and international law including the United Nations Convention on the Law of the Sea”. It said America “exaggerates the situation in the region and attempts to sow discord between China and other littoral countries”. The accusation is completely unjustified. The Chinese side is firmly opposed to it.” (Global Conflict Tracker, 2020)

For its part, China must carefully assess that such actions are in its own interests. As many scholars have pointed out, anytime a rising power attains a certain level of might, a security dilemma is likely to spark.



(2010), M., 2020. Min Gyo Koo – Island Disputes And Maritime Regime Building In East Asia- Between A Rock And A Hard Place (The Political Economy Of The Asia Pacific) (2010). [online] Docme.ru.Availableat: https://www.docme.ru/doc/1271471/ [Accessed 16 September 2020].

Affairs, C. and Current Affairs February, 2., 2020. Current Affairs February 2018 PDF | Ebook |Free Download.[online]Examveda.com.Available at: https://www.examveda.com/current-affairs-february-2018-pdf-ebook/ [Accessed 16 September 2020].

Fas.org. 2020. [online] Available at: https://fas.org/sgp/crs/row/R44072.pdf [Accessed 16 September 2020].

Broderick, K., 2015. Chinese Activities In The South China Sea Implications For The American Pivot To Asia. [online] Project2049.net. Available at: https://project2049.net/wp-content/uploads/2018/06/150511_Broderick_Chinese_Activities_South_China_Sea_Pivot.pdf [Accessed 16 September 2020].

Liberapedia. 2020. Cabbage Strategy. [online] Available at: https://liberapedia.wikia.org/wiki/Cabbage_Strategy [Accessed 16 September 2020].

SAGE Journals. 2020. Drawing The U-Shaped Line: China’S Claim In The South China Sea, 1946–1974 – Chris P. C. Chung, 2016. [online] Available at: https://journals.sagepub.com/doi/abs/10.1177/0097700415598538 [Accessed 16 September 2020].

Mitchell, M., 2016. The South China Sea: A Geopolitical Analysis. Journal of Geography and Geology, 8(3), p.14.

Nguyen, H., 2020. Vietnam’s Position On The Sovereignty Over The Paracels & The Spratlys: Its Maritime Claim.

Lowyinstitute.org. 2020. South China Sea. [online] Available at: https://www.lowyinstitute.org/issues/south-china-sea [Accessed 16 September 2020].

Global Conflict Tracker. 2020. Territorial Disputes In The South China Sea | Global Conflict Tracker. [online] Available at: https://www.cfr.org/global-conflict-tracker/conflict/territorial-disputes-south-china-sea [Accessed 16 September 2020].

United States Department of State. 2020. U.S. Position On Maritime Claims In The South China Sea – United States Department Of State. [online] Available at: https://www.state.gov/u-s-position-on-maritime-claims-in-the-south-china-sea/ [Accessed 16 September 2020].


Autore dell’articolo*: Alessandra Palmeri, specializzata in Relazioni Internazionali alla Nankai University di Tianjin e Dottoressa in lingue e culture e società dell’ Asia e Africa Mediterranea presso la Ca’ Foscari di Venezia.


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