The United Nations Convention on the Law of the Sea (UNCLOS) reflects a series of compromises between the ocean’s various stakeholders and seeks to preserve maritime stability by ensuring tensions do not build to the point of conflict. As it opened for signature in 1982, states began organising their maritime claims and activities around its four key elements (see Box 1), which transformed and stabilised the maritime domain. The People’s Republic of China (PRC), however, is systematically and dangerously undermining each of these foundational elements, threatening to return the global maritime domain to its former state of instability. If the UNCLOS system is to be preserved, states with important maritime interests, including the United Kingdom (UK), must reinforce its provisions with clear policy statements, support affected stakeholders actively, and employ stiffer action where required. Without such efforts, the future order of the oceans is in doubt.
The key elements of UNCLOS
Beginning in the early 20th century, advancements in military technologies, notably the capacity to drill offshore for oil and gas, and expanded industrial fishing, put pressure on states to establish international laws to regulate activities at sea. It was not until after the Second World War, however, that states were able to address these pressing issues. In 1982, negotiators completed a comprehensive treaty to provide order, stability, and sustainable productivity in the world’s oceans. To achieve these aims, UNCLOS advances four interwoven areas of international law.
First, it defines maritime zones and establishes the bases for delimiting them. It is the first international treaty, for instance, to establish a uniform maximum breadth of the territorial sea at 12 nautical miles and creates the 200-nautical mile exclusive economic zone (EEZ) within which coastal states possess sovereign rights to the resources inside it. It provides a system to delimit maritime zones between neighbours based on coastal geography, international law, and equitable results. These important advancements brought rapid and substantial uniformity to maritime claims around the world and stability to what had previously been a global patchwork.
Second, UNCLOS defines the rights and duties which apply within its several maritime zones. It balances the security and economic interests of coastal states against the freedoms of maritime states to navigate and operate freely on the seas. In doing so, it provides for various passage regimes, including the right of innocent passage in the territorial sea, which requires ships to pass in an un-threatening manner, and transit passage, which grants ships and aircraft the right to pass through narrow coastal straits. In the rest of the oceans, it preserves the right of high seas freedoms, excepting only a coastal state’s right to the resources and related jurisdiction in its EEZ and continental shelf.
Third, UNCLOS establishes rules, standards, and norms to protect the maritime environment. It views the resources in and under the high seas as the ‘common heritage of mankind’. It gives coastal states jurisdiction to protect and preserve the marine environment and requires them to undertake measures to avoid over-exploitation of living resources. Further, it requires cooperation between neighbouring states to conserve living resources and to prevent marine pollution and other environmental damage. It requires environmental assessment prior to undertaking action which may cause substantial pollution.
Fourth, and finally, UNCLOS establishes a mandatory system to resolve disputes and advance maritime stability. It obliges states to settle disputes by peaceful means, allows parties to choose their own dispute resolution methods, and establishes processes among which states can choose to adjudicate disputes. It even lets states opt out of the most contentious types of disputes, such as those involving sovereignty over territory, military activities, and law enforcement.
Box 1: Four key elements of UNCLOS
- Defining maritime zones
- Establishing rules for delimiting maritime boundaries between states
- Establishing rules for delimiting national and international zones
- Balancing coastal state rights and international freedoms
- Balancing coastal state security and offshore military activities
- Protecting the marine environment
- Shielding the marine environment as the common heritage of humankind
- Protecting presumptions of environmental protection and sustainable use
- Stabilising through the dispute resolution process
- A mandatory process where the application of the rules is questioned
How the PRC undermines the law of the sea
The PRC is putting pressure on each of these four elements. Beijing asserts it has ancient rights to make maritime claims its own way, despite its ratification of UNCLOS in 1996, and claims domestic jurisdiction to enforce them. In doing so, it weakens the principles underpinning UNCLOS, leaving international law of the sea in danger of further unravelling.
Defining maritime zones
The PRC upends completely the rules and principles of UNCLOS for claiming and delimiting maritime zones. To begin with, the PRC’s nine-dash line claim in the South China Sea (see Map 1) is entirely divorced from the cardinal principle that the land dominates the sea. Based on this line, the PRC asserts historic rights to roughly 2.7 million square kilometres of water space. This staggering claim was considered and rejected fully in 2016 by the panel of international law judges and experts which formed the arbitral tribunal in a case against the PRC initiated by the Philippines. These experts determined that Beijing’s claim has no basis in international law, and yet since 2016 the PRC has escalated its use of coercion to force acceptance of its claims. The effect is to deny Vietnam, the Philippines, Malaysia, and Indonesia the resource rights which international law unambiguously allocates to them.
Map 1: The Chinese perspective of the Pacific region
Balancing coastal state rights and international freedoms
The PRC’s domestic law upsets the internationally accepted balance of economic and security rights and duties between coastal and maritime states. Beijing claims the right to deny innocent passage to warships in its territorial sea and to prohibit information gathering in its EEZ. It regularly interferes with lawful intelligence operations, military surveys, and operations of vessels of other states. It performs dangerous aerial intercepts and takes other coercive and risky actions. In November 2023, for instance, a Chinese ship employed active sonar near an Australian naval vessel with divers in the water untangling a fishing net stuck in its propeller. The divers suffered predictable injuries. More recently, the PRC employed water and acoustic cannons against Philippine vessels and their crews near a disputed reef. These were astonishingly brazen violations of international law.
Protecting the marine environment
The environmental provisions of UNCLOS require states to protect and preserve the marine environment. The PRC flouted this duty in the South China Sea when it destroyed coral reefs and the complex habitats around them to build seven new islands and their military bases between 2013 and 2015. The South China Sea’s rich biodiversity was degraded significantly as the PRC dredged up 100 square miles of healthy coral reefs to build 3000 acres of newly formed island fortresses. The PRC’s reclamation activities also violated the requirements to cooperate with other states to avoid harmful environmental effects, to preserve fragile ecosystems, and to perform and publish environmental assessments in advance of taking action. That Beijing ignored each of these duties was confirmed in the 2016 arbitral decision in the South China Sea case.
Further, overfishing is a global problem to which the PRC contributes disproportionately. With 2500 registered (and up to 17,000 unregistered vessels), the PRC’s distant-water fishing fleet is a major contributor to the pressure on global fish stocks. In the South China Sea alone, large fish stocks have decreased by 90% since 2000. The PRC was found by the South China Sea arbitral tribunal to be in breach of its obligations to protect rare or fragile species by allowing its fishers to harvest giant clams on a significant scale.
Finally, the PRC is a major force at the International Seabed Authority, which was established to regulate seabed mining on and under the seabed beyond national jurisdiction. Through this organisation, the PRC holds substantial rights to explore and exploit rich mineral areas in the central Pacific Ocean and has been pushing for an early start to seabed mining before environmental impacts are well studied. Together these actions demonstrate the PRC’s systematic disregard for UNCLOS provisions designed to protect the environment.
Stabilising through the dispute resolution processes
As noted above, the mandatory dispute resolution processes in UNCLOS ensure that bargains made amongst various stakeholders are maintained without resorting to conflict. Further, the convention specifies that no reservations may be made to its provisions. States must either opt in, and receive UNCLOS’s benefits and accept its burdens, or remain an outsider.
The PRC has indeed accepted the benefits of the convention. A Chinese judge sits on the International Tribunal for the Law of the Sea and has done so since the tribunal’s inception in 1996. The PRC made submissions to the Commission on the Limits of the Continental Shelf and is a very active participant in developing the rules of the International Seabed Authority. But Beijing refuses the convention’s burdens. One Chinese diplomat referred to her country’s position on the South China Sea arbitration this way:
Beijing’s position is clear: no acceptance, no participation, no recognition, and no implementation.
The PRC’s Ministry of Foreign Affairs has also declared that ‘the award is null and void and has no binding force. China neither accepts nor recognises it.’ Instead, the PRC has steadily increased its at-sea coercion against the Philippines. Thus, one of the most powerful parties to UNCLOS chose to flex its power, rather than to adhere to its explicit treaty commitments.
Conclusion: Why does the PRC’s behaviour matter?
Until the PRC’s challenge, UNCLOS had brought decades of steadily advancing maritime order and stability because it provided a single set of rules which balanced fairly the interests of all states. But the PRC’s approach to the four foundational elements of UNCLOS has steadily gutted the universality of its provisions.
As a state with substantial power and influence in the international system, the PRC is inherently, and inescapably, a rule-maker. In breaking down the careful tradeoffs in UNCLOS, the PRC creates room for others to follow its approaches and threatens to reverse historical advances in maritime order.
The United States supports UNCLOS but frustratingly remains outside it. Push back inside the convention’s institutions therefore must come from the UK, Australia, Japan, India, France, and others with substantial maritime interests. Otherwise, rather than being a century of maritime tranquillity, the years ahead will see a detrimental reversion to maritime instability.
Peter Alan Dutton is a professor in the Stockton Centre for International Law at the US Naval War College. The views expressed are his personal views and are not meant to represent the views of the US Navy or any agency of the US government. This article was produced with support from the Norwegian Institute for Defence Studies.
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