South China Sea arbitral award remains cornerstone of sovereignty, international law 10 years later

Lt. Col. Richard J. Connaroe II/U.S. Army 8th Theater Sustainment Command

On March 24, 2026, the China Coast Guard (CCG) declared “clearing operations” at Scarborough Reef, broadcasting coordinates by live radio for a rectangular exclusion zone and ordering all vessels to vacate the area between 11 a.m. and 6 p.m. To enforce this illicit directive, Beijing deployed at least six CCG vessels, 15 maritime militia vessels and a People’s Liberation Army Navy warship. Using dangerous maneuvers and intimidation tactics, CCG rigid-hull inflatable boats drove away dozens of Philippine fishing vessels. More than 20 fishing boats remained despite China’s harassment.

Beijing’s actions violated international law and the legally binding 2016 award of an arbitral tribunal constituted under the United Nations Convention on the Law of the Sea (UNCLOS). As the international community marks the 10th anniversary of that landmark ruling, the significance of the arbitral award in the case the Philippines brought has grown more evident.

The tribunal’s comprehensive rejection of China’s expansive maritime claims established critical legal precedents that continue to shape maritime disputes across the Indo-Pacific. Yet China’s wholesale rejection of, and persistent refusal to comply with, the tribunal’s findings — exemplified by regular coercion targeting the Philippines, such as the March 2026 harassment, remains a security and stability challenge in the South China Sea and across the Indo-Pacific.

2012 Standoff Sparks Case

Scarborough Reef is where the path to the 2016 award began with a tense confrontation. On April 8, 2012, a Philippine aircraft spotted eight Chinese fishing vessels anchored at the reef. Although Manila and Beijing claimed sovereignty over the reef at that time, the Philippines essentially controlled the area, with its Navy regularly detaining or expelling fishing crews operating in violation of Philippine law.

When a Philippine Navy frigate arrived April 10 to investigate, Sailors boarded and inspected the Chinese vessels, finding corals, giant clams and live sharks that fishermen had collected in violation of Philippine law. The trawlers sent a distress call to authorities in China, and two unarmed China Marine Surveillance vessels patrolling nearby arrived quickly, positioning themselves outside the reef’s narrow mouth and initiating a standoff that would last more than two months.

Manila pursued a diplomatic solution, de-escalating and demilitarizing on April 12, replacing the Navy frigate with a Coast Guard ship. Following talks the next day between the Philippine foreign secretary and China’s ambassador in Manila, Chinese cutters escorted the trawlers from the reef, leaving each side with one vessel. However, negotiations collapsed over the rights to the fishermen’s catch and the withdrawal sequence, prompting a stalemate and the return of a second Chinese vessel.

Over the following weeks, the situation worsened. The Philippines sought arbitration through the Association of Southeast Asian Nations (ASEAN), but China demanded bilateral negotiation and escalated its presence. By May 21, dozens of Chinese vessels faced off against two Philippine vessels at the reef.

On June 15, the Philippines withdrew its vessels, but the Chinese ships stayed — accounts differ on whether this followed a mutual withdrawal agreement or was a unilateral decision by the Philippines to avoid an approaching typhoon. Regardless, Chinese ships remained, effecting a de facto transfer of control. By July, China was forcing Philippine fishing boats away from the reef.

The failure of bilateral negotiations and regional diplomacy — including ASEAN’s inability to issue a joint communique — led Manila to turn to international arbitration under UNCLOS.

A Baseless Claim: the ‘Nine-Dash Line’

Central to the dispute was China’s assertion of “historic rights” within an ambiguous boundary that Beijing refers to as the “nine-dash line,” which marks its claim to an expanse of the South China Sea. This demarcation originated in 1947 when the Republic of China (ROC) published a map depicting an 11-dash, U-shaped line encompassing roughly 90% of the South China Sea. ROC geographer Yang Huairen developed the boundary while cataloging what the government considered China’s maritime territories after World War II.

In 1952, three years after taking power, the Chinese Communist Party (CCP) modified the demarcation, eliminating two dashes in the Gulf of Tonkin under an agreement with Vietnam.

What the nine-dash line purports to signify has never been clearly defined, even within China. The ambiguity centers on whether it represents a claim to all maritime territory within the boundary or merely to the geographic features contained within. Some Chinese scholars characterize it as encompassing “the ocean, islands and reefs,” while simultaneously maintaining that its discontinuous nature permits international passage. Others offer narrower interpretations focused solely on territorial features rather than surrounding waters.

This fundamental ambiguity became a critical legal weakness for Beijing. The demarcation predates UNCLOS, which China signed in 1982 and ratified in 1996. UNCLOS establishes maritime entitlements through a comprehensive framework based on geographic features and coastal state rights, not historical assertions or cartographic boundaries. Under this legal regime, ambiguous dotted lines drawn on mid-20th century maps cannot serve as the basis for maritime claims.

International Arbitration

Following the 2012 standoff, the Philippines initiated arbitration proceedings under UNCLOS Annex VII in January 2013. The case, formally titled “The Republic of the Philippines v. The People’s Republic of China,” asked the tribunal to rule on the lawfulness of China’s claims and actions in the South China Sea.

China initially participated in the tribunal, submitting a 2014 position paper refuting jurisdiction. Regardless, under Article 9 of Annex VII, the arbitration could proceed even without China. The tribunal of five international jurists examined China’s jurisdictional objections and the merits of the case.

Both parties understood that the tribunal’s award would be legally binding. UNCLOS Article 296 explicitly states that decisions of tribunals constituted under the convention are “final and shall be complied with by all the parties to the dispute.” This was not an advisory ruling — it was adjudication with the force of international law.

A Comprehensive Rejection of China’s Claims

On July 12, 2016, the arbitral tribunal issued its unanimous award. Most significantly, it ruled that China’s claims to historic rights within the nine-dash line have no legal basis insofar as they exceed the maritime entitlements permitted under UNCLOS. The arbitral award stated that UNCLOS comprehensively governs legal rights and maritime entitlements in the South China Sea. Beijing could not claim rights beyond what UNCLOS allows based on mere historical assertions.

The tribunal also examined the maritime entitlements of features in the Spratly Islands and at Scarborough Reef. It determined that all naturally occurring high-tide features in these areas are “rocks” under UNCLOS Article 121(3) — meaning they are entitled only to a 12-nautical-mile territorial sea, not to an exclusive economic zone (EEZ) or continental shelf. This finding dramatically reduced the maritime space China could legally claim, even if it possessed sovereignty over the features themselves.

Under UNCLOS, a “rock” is a term that refers to an island that cannot sustain human habitation or economic life of its own.  A rock receives a territorial sea but not an EEZ.  Scarborough Reef is a rock, because it is a high-tide elevation that is not an island. The 2016 tribunal correctly ruled the same, that Scarborough Reef was a rock rather than an island or a low-tide elevation.

Additionally, the tribunal found that China violated the Philippines’ sovereign rights by interfering with lawful activities permitted under UNCLOS. This included unlawfully preventing Philippine crews from fishing at Scarborough Reef, which the tribunal recognized as a traditional fishing ground for fishermen from multiple countries, including the Philippines.

Finally, the tribunal ruled that China violated its obligations under UNCLOS to protect and preserve the marine environment by allowing its fishing fleet to engage in harmful practices and by causing severe and irreparable harm to coral reefs through large-scale land reclamation. Further, the tribunal found China’s construction of artificial islands to be unlawful and further aggravation of the dispute.

The arbitral award’s significance extended beyond its specific findings. It established that UNCLOS provides the comprehensive legal framework for maritime disputes, that historical claims cannot override UNCLOS provisions and that coastal states’ rights within their respective EEZ must be respected. These principles apply not only to the South China Sea but also to maritime disputes worldwide.

China Rejects Ruling, Escalates Coercion

Despite the unanimous binding decision, Beijing declared the ruling “null and void” and dismissed it as “nothing but a piece of wastepaper.” On July 18, 2016, six days after the arbitral award, Beijing sent People’s Liberation Army bombers on “normal battle patrols” over Scarborough Reef. In the decade since, China has escalated its coercive activities in the region.

Chinese vessels repeatedly and regularly harass and intimidate Philippine vessels operating lawfully within the Philippines’ EEZ. CCG and maritime militia ships have rammed, blocked and fired high-powered water cannons at Philippine civilian, government, and military vessels, damaging the boats and injuring their crew.

In October 2025, Manila reported Chinese fishing crews using cyanide, a poisonous chemical, near Second Thomas Shoal while operating under the protection of the CCG and maritime militia. This practice causes indiscriminate and permanent destruction of vital coral reefs, violating UNCLOS Articles 192 and 194, which require states to protect and preserve the marine environment and prevent pollution.

Beijing’s so-called clearing operations at Scarborough Reef in March 2026 represent one of its latest escalations. By declaring an exclusion zone and deploying more than 20 vessels to enforce it, China sought to assert authority it does not legally possess. The reef is about 120 nautical miles from the Philippine island of Luzon, well within the Philippines’ 200-nautical-mile EEZ. Under UNCLOS Articles 56 and 57, the Philippines exercises sovereign rights in this area for exploring, exploiting, conserving and managing natural resources. The 2016 arbitral award confirmed these rights and found that waters beyond the reef’s 12-nautical-mile territorial sea fall within the Philippines’ EEZ.

Arbitral Award Remains Vital Today

The 2016 South China Sea Arbitral Award remains a cornerstone of international maritime law and a critical reference point for resolving disputes peacefully through legal mechanisms rather than coercion. The award established binding precedents that clarify maritime entitlements under UNCLOS. Its rejection of historic rights claims that exceed UNCLOS provisions prevents states from unilaterally asserting control over vast maritime areas based on ambiguous assertions. Its findings on the status of maritime features provide clear guidance for determining what entitlements — territorial seas, EEZ or continental shelves — different features can generate.

The Philippines exercised a lawful right under UNCLOS to initiate and resolve a maritime dispute peacefully and in accordance with international law. The tribunal’s decision represents international law functioning as intended: a mechanism for resolving disputes through legal adjudication rather than force. China’s decade of noncompliance does not diminish the arbitral award’s validity or significance. Rather, it highlights the ongoing need for the global community to recognize China’s broad pattern of selective application of international law; protect sovereign rights and global commons; and maintain freedom of navigation and overflight without fear of the use of force.

By ignoring a legally binding tribunal decision and continuing to assert unlawful claims through coercion, Beijing demonstrates a view that international law applies only when it benefits China’s interests. This undermines the legal framework that all nations depend upon for peaceful dispute resolution. The erosion of legal norms threatens maritime security, freedom of navigation and economic prosperity across the Indo-Pacific and beyond.

Collective Action by Allies, Partners

Upholding the arbitral award requires collective commitment. Aggression or coercion that demonstrates a “might makes right” approach destabilizes the region. The international community must conduct freedom of navigation operations that challenge excessive maritime claims; operate lawfully within their EEZs despite interference; and publicize coercive behavior — such as China interfering with Philippine fishing at Scarborough Reef.

As the March 2026 incident demonstrates, the legal principles established in the arbitral award remain as relevant today as they were 10 years ago. The tribunal’s findings continue to define the lawful boundaries of maritime claims and the rights of coastal states. Only through collective resolve in upholding these norms can the international community ensure a free, secure and prosperous Indo-Pacific, and preserve the legal framework that protects the sovereign rights of all nations and maintains the freedom of the seas upon which global commerce and security depend.

The U.S. Army 8th Theater Sustainment Command, National Security Law Team, is based in Hawaii.