On October 20, China accused a U.S. naval vessel of “undermining regional stability” by entering waters near Sabina Shoal in the Spratly Islands. According to a spokesperson for the People’s Liberation Army’s Southern Theater Command Navy, the U.S. Littoral Combat Ship USS Charleston (LCS-18) “illegally ​intruded” into waters adjacent to Sabina Shoal “without approval from the Chinese government.” By contrast, a U.S.​ Navy 7th Fleet spokesperson maintained that the Charleston conducted “routine operations in international waters” consistent with international law.

This latest naval encounter reflects the long-standing legal dispute between China and the U.S. over the freedom of navigation of warships in the South China Sea. What makes it distinct is the location of the incident: unlike all previous U.S. Freedom of Navigation Operations (FONOPs) targeted at China in the South China Sea, the encounter occurred near Sabina Shoal, a maritime feature not occupied by China. Thus, this is also the first time that the PLA Navy (PLA) officially admitted that it “dispatched forces to track and monitor the U.S. vessel” near a feature China doesn’t occupy. 

This new kind of close encounter may reveal that the Chinese government is upgrading its strategy to respond to perceived U.S. naval intrusions in the South China Sea. At the same time, the incident may also serve as a warning to the Philippines, which considers Sabina Shoal to be a part of its Exclusive Economic Zone (EEZ). These interpretations remain tentative, and non-exclusive, but they make the encounter worth examining beyond the immediate exchange of official statements.

Disputes Between China and the U.S. over “Freedom of Navigation” of Warships 

The United States holds that the right to sail and operate its military vessels “wherever customary international law allows” is “a long-standing national interest.” The U.S. military uses FONOPs to challenge maritime claims and restrictions that it considers excessive. 

China, by contrast, argues that freedom of navigation cannot be invoked to justify activities that it views as threatening its territorial integrity or security, including foreign warships’ operations near maritime features over which China asserts sovereignty. Beijing considers the intentional “intrusion” of warships into its claimed territorial sea to be “hegemonic freedom of navigation.” China argues U.S. FONOPs have no place in contemporary international law. 

A semi-official research report published by the China Institute for Marine Affairs under the Ministry of Natural Resources in August 2025 highlighted this issue. The report concluded that the “U.S. Freedom of Navigation lacks a basis in international law and seriously distorts the interpretation and development of international law.” These competing positions have underpinned repeated Chinese protests against U.S. naval operations in the South China Sea.

Notably, news reports of the Charleston’s October 20 operation did not officially describe it as a FONOP. The U.S. spokesperson’s statement instead emphasized that “all nations enjoy freedom of navigation and other lawful uses of the sea in this area.” That language is consistent with Washington’s broader position on maritime access, but it does not establish that the operation was a formally designated FONOP or identify the specific legal claim, if any, that the vessel intended to challenge. 

The distinction matters: a naval transit, a routine operation, and a FONOP may overlap in practice, but they are not necessarily interchangeable descriptions of an operation’s purpose.

Why Sabina Shoal Is Distinct

U.S. FONOPs generally identify a particular maritime claim or restriction they seek to challenge.  For instance, the United States explicitly labeled a previous operation that took place on August 13, 2025, near Scarborough Shoal as a FONOP intended to challenge Chinese domestic legislation requiring prior authorization for foreign warships to enter China’s territorial sea. In such cases, the stated legal objective provides a relatively clear basis for interpreting the operation and anticipating a Chinese response. In the August 2025 case, the PLA said it had “organized forces to lawfully track, monitor, issue warnings, and expel the U.S. warship.” 

Sabina Shoal presents a different situation for a number of reasons. First of all, unlike Scarborough Shoal, Sabina Shoal was not among the contested maritime features in the 2016 South China Sea Arbitration Award. 

At the same time, there is no mutual understanding between China and the Philippines on the legal status of the shoal and its surrounding waters. The United States and the Philippines regard Sabina Shoal as a low-tide elevation that cannot, in its own right, generate a territorial sea. They thus regard the surrounding waters as part of the Philippines’ EEZ. 

By contrast, the Chinese government disputes that Sabina Shoal (known in Chinese as Xianbin Jiao) is a low-tide elevation. In fact, a “Survey Report on the Coral Reef Ecosystem of Xianbin Jiao” published by the Ministry of Natural Resources of China in August 2024, said that there are at least three naturally formed cays above water at high tide. Accordingly, China considers Sabina Shoal to be a rock that can claim a territorial sea. This may explain why China accused the Charleston of an “illegal intrusion” into the “adjacent waters” of Sabina Shoal. 

Nevertheless, the most peculiar scenario at Sabina Shoal is that this maritime feature has never been formally occupied by China, thanks to the 2002 Declaration on the Conduct of Parties in the South China Sea (DOC), which prohibits “inhabitation” on previously unoccupied maritime features. 

Yet in Beijing’s view, Sabina Shoal is part of the “Nansha Qundao” (Spratly Islands), which as a whole belongs to China. That might be the reason that China never formally claimed any territorial sea around its occupied maritime features such as Johnson Reef (Chigua Jiao), Fiery Cross Reef (Yongshu Jiao), or Cuarteron Reef (Huayang Jiao). Instead, Beijing claims “indisputable territorial sovereignty, sovereign rights and interests” within the whole of the Spratly Islands group.

The ambiguity surrounding the nature of the Charleston’s operation makes it difficult to interpret. It’s unclear if the United States intended to challenge a Chinese claim to maritime entitlements around Sabina Shoal or a requirement for prior authorization of transiting its territorial sea. If, however, the operation was instead intended to demonstrate support for the Philippines, the significance would lie less in a specific legal challenge than in the strategic signal conveyed by a U.S. naval presence near a flashpoint in the China-Philippines dispute.

A Possible Warning to the Philippines

The encounter occurred amid heightened tensions between China and the Philippines. On October 14, Chinese Ambassador to the Philippines Jing Quan reportedly remarked that China could “easily win a conflict” against the Philippines if it chose to use force. The remark followed a serious confrontation between a Chinese Coast Guard vessel and a Philippine government vessel at Sabina Shoal on September 18. 

In fact, since the beginning of October, at least eight close encounters between China and the Philippines have occurred across the South China Sea and Luzon Strait, according to Reuters. This wider context helps explain why the Philippines might view the Charleston’s presence at Sabina Shoal as a sign of U.S. support, even if the operation was not formally identified as a FONOP against Chinese maritime claims.

China’s response, on the other hand, could be interpreted as a fresh warning to the Philippines. By dispatching naval forces to track and monitor the U.S. warship at an unoccupied maritime feature for the first time, China showcased its determination to protect its claimed rights and interests at Sabina Shoal. 

This upgraded response also sends a straightforward warning to the Philippines that any further provocation at Sabina Shoal, with or without support from the U.S., will predictably receive an escalated Chinese response.

The Outlook of China-U.S. Naval Encounters in the South China Sea 

While international law provides a common framework for maritime conduct, its interpretation and application remain deeply contested by major powers. The United States advocates its naval operations as a defense of freedom of navigation, whereas China views U.S. naval operations near South China Sea maritime features as challenges to its territorial sovereignty and security. Without a shared understanding of the legal and strategic implications of such operations, similar encounters are likely to recur.

The outlook is therefore one of persistent competition accompanied by risks of unintended escalation. As both navies maintain a significant presence in the South China Sea, close encounters – including, as in this case – China-U.S. naval encounters at maritime features not occupied by China, may become increasingly frequent, particularly amid intensifying Philippine-U.S. security cooperation. Even when neither side seeks confrontation, miscalculation, communication failures, or domestic political pressure could turn a “routine operation” into a serious crisis.

Yet confrontation is not inevitable. Both China and the United States have strong incentives to prevent tactical incidents from escalating into broader military conflict. Maintaining effective military communication channels, strengthening incident-management mechanisms, and clarifying operational protocols should therefore remain priorities. Equally important is a willingness to address maritime disagreements through diplomacy and international law rather than relying exclusively on military assertions such as the FONOPs.

Ultimately, the significance of the Sabina Shoal naval encounter lies not simply in the actions of the two navies, but in what it reveals about the future of maritime order in the South China Sea. Whether such encounters become catalysts for escalation or opportunities for improved crisis management will depend on the strategic choices made in Beijing and Washington.