Explainer: The Philippines-China Maritime Dispute and International Law Features
rjames1045 / Pixabay
Explainer: The Philippines-China Maritime Dispute and International Law

Through 2023, tensions in the South China Sea between China and the Philippines have escalated, marked by such significant escalations as the removal of a floating barrier by the Philippines near the Scarborough Shoal and the deployment of its Coast Guard amid increased activity by the Chinese Maritime Militia (CMM) near Julian Felipe Reef (or Whitsun Reef). These incidents underscore the long-standing territorial disputes in this heavily trafficked shipping lane, and underpin a growing global maritime conflict.

Who are the parties involved in the territorial dispute?

There are three key parties involved in the current South China Sea territorial dispute: China, the Philippines, and the US.


China has long claimed much of the South China Sea under its Nine-Dash Line approach to territorial integrity. The Nine-Dash Line refers to maps produced by China that allege that China has a territorial claim on what it states are not “shoals” or “low-tide land masses” but islands in the South China Sea. If they are islands under Chinese control, this would expand China’s territory under international maritime law. China has never clarified if this means the area is part of China’s Exclusive Economic Zone (EEZ), meaning the country has full control of economic activity in the area used, or if China merely views the area as under its jurisdiction, implying a more moderate level of control. China has attempted to strengthen its claim by “reclaiming” islands in the area via dredging; however, many countries have asserted these are completely artificial islands rather than “reclaimed” islands.

There are two main Chinese organizations in the South China Sea asserting China’s claims. The first is the Chinese Coast Guard (CCG). The CCG is a branch of the Chinese military and is the most official Chinese organization enforcing China’s asserted territorial integrity. The second Chinese group in the South China Sea is the Chinese Maritime Militia (CMM). The CMM was established in the 1960s when China set up multiple maritime militia schools for fishermen. Starting in the 1970s, China began to use the CMM to assert its claims of sovereignty. While the CMM is an officially sanctioned Chinese organization, it is not an official branch of the military.

The Philippines

The Philippines’ territorial claims in the South China Sea (which it calls the West Philippine Sea) are largely based on historical fishing ground claims. The country also asserts that what China claims are “islands” are actually “low-tide land masses” and shoals, which are therefore part of the Philippines’ EEZ. Starting in the 1970s, the Philippines began strongly asserting its territorial ownership of the Scarborough Shoal and other nearby shoals and land masses.


The US began its heavy involvement in the area on behalf of the Philippines in the South China Sea around 2015, when it began to hold regular “freedom of navigation operations” (FONOP) in the region. However, the US has had a reciprocal ally relationship with the Philippines since 1951, including bases and military presence on the Philippines’ territory. Ever since 2015, the US has held regular military exercises in the South China Sea in support of the Philippines, with the most recent taking place in November.

Other countries with territorial claims

There are several other countries with competing territorial claims in the South China Sea, including Brunei, Indonesia, Japan, Malaysia, Taiwan, and Vietnam.

Relevant International Law:

2016 Arbitral Agreement

The territorial dispute between China and the Philippines reached a head in 2013 when the Philippines brought a case against China in the Permanent Court of Arbitration (PCA) in the Hague challenging China’s territorial claims. The PCA released its ruling in 2016, largely siding with the Philippines in the territorial dispute. The PCA ruling (also called the 2016 Arbitral Agreement) stated that China’s Nine-Dash Line territorial claims were not legally supported; China violated the Philippines’ territorial integrity, and China’s reclamation activities in the disputed area violated international environmental law. China has since rejected the ruling and continued claiming territorial rights in the area. This agreement is the primary source of international law used by both the Philippines and the US to assert the area near the Scarborough Shoal is part of the Philippines’ EEZ.


The United Nations Convention on the Law of the Sea (UNCLOS) is the second key source used by the US and the Philippines to assert the disputed area is part of the Philippines’ EEZ. Three key sections of UNCLOS apply to the territorial dispute. The first is Section 2 Article 3, which states, “Every State has the right to establish the breadth of its territorial sea up to a limit not exceeding 12 nautical miles, measured from baselines determined in accordance with this Convention.” But what are the baselines from where the 12 nautical mile measurement should start? This question is answered by the second important part of UNCLOS, Section 2 Article 13. Article 13 states:

  1. A low-tide elevation is a naturally formed area of land which is surrounded by and above water at low tide but submerged at high tide. Where a low-tide elevation is situated wholly or partly at a distance not exceeding the breadth of the territorial sea from the mainland or an island, the low-water line on that elevation may be used as the baseline for measuring the breadth of the territorial sea.
  2. Where a low-tide elevation is wholly situated at a distance exceeding the breadth of the territorial sea from the mainland or an island, it has no territorial sea of its own.

This article is one of the reasons why China has attempted to claim that some of the shoals in the area are islands and has attempted to “reclaim” islands nearby. If they are islands, then China could measure its baseline from the “low-tide elevation” in dispute, as it would be situated “at a distance not exceeding the breadth of the territorial sea from…an island.” However, the 2016 Arbitral Award dismissed this interpretation, ruling that the “islands” in question were not islands, making the “low-tide elevations” part of the Philippines’ EEZ.

The third important part of UNCLOS is Part 8, Article 121, which governs what is and is not an island. Article 121 states, “An island is a naturally formed area of land, surrounded by water, which is above water at high tide…Rocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone or continental shelf.” This article was one of the key sections of UNCLOS cited in the 2016 Arbitral Award, as the “islands” China alleged its territorial area emanated from were determined to be uninhabitable, and therefore did not provide justification for China’s territorial claims.   

COLREGS and the 2002 ASEAN China Declaration

While the Arbitral Agreement and UNCLOS are the two main maritime legal instruments relevant to the South China Sea territorial dispute, two other legal documents have been referenced during the ongoing conflict. The first is the International Regulations for Preventing Collisions at Sea (COLREGS). These international maritime regulations specifically govern collisions, both purposeful and accidental, and have come up recently during an incident in which an alleged CMM vessel rammed a PCG vessel. The second is the 2002 ASEAN China Declaration, which was a declaration agreed to by China and the members of the Association of Southeast Asian Nations (including the Philippines), committing the signatories to peaceful resolutions of territorial disputes and freedom of passage within the South China Sea.

Increasing tensions in 2023:

2023 has been a year marred by increased tensions between China and the Philippines in the South China Sea. In September, the Philippines removed a floating barrier near the Scarborough Shoal, which the PCG alleged was placed by China. The PCG also claimed that the CCG hailed and harassed several Filipino fishermen in the area. In November, President Xi Jinping of China and Philippine President Ferdinand “BongBong” Marcos Jr. met during the APEC conference in San Francisco, US, and discussed the ongoing tensions. Days later the US and the Philippines held military exercises in the disputed area. Then, in early December, the PCG deployed two ships to the Julian Felipe Reef in response to an alleged increase in CMM activity. Most recently, the Philippines summoned the Chinese ambassador to the Philippines after an incident in which a boat carrying the Philippine Chief of Staff of the Armed Forces, General Romeo Brawner was allegedly sprayed with water cannons and rammed by a CMM vessel. The CCG has denied these allegations.

Why is the South China Sea important?

The South China Sea is an incredibly important area, as it is one of the busiest shipping lanes in the world, with over $5.3 trillion in goods moving through it. The area is also rich in oil and natural gas, with some estimates putting the total oil and gas content at over 11 billion barrels of oil and 190 trillion cubic feet of natural gas.