Chinese Buoys Near the South Korea-China PMZ

Key Findings

• This report focuses on China's marine observation buoys in and adjacent to the Provisional Measures Zone (PMZ) in the waters between China and South Korea.
• Most of the buoys appear to be consistent with a standardized Chinese type of 10-meter ocean environmental monitoring buoy, exhibiting a lighthouse-style design featuring a circular floating base, central vertical tower, and an upper platform.
• Some are equipped with solar arrays, which means they are intended for long-duration autonomous operation and probably contain instruments that require consistent energy input, such as environmental sensors, AIS receivers, or communication modules.
• Photographs alone cannot confirm the full range of the buoys' functions, but one cannot preclude the possibility of dual-use capabilities. More information provided by governments about the precise locations of the buoys would enable more detailed analysis by researchers.
• Regardless of the buoys' capabilities, their placement within and adjacent to the PMZ is itself consequential in demonstrating China's strategic intent in the Yellow Sea (West Sea). Typical of China's grey zone tactics, all but one of the buoys are deployed both outside the PMZ and on China's side of a theoretical median line drawn between China and South Korea's overlapping EEZ claims, indicating an effort to increase presence in disputed waters while avoiding the direct provocation of placing most inside the PMZ.
• Based on China's militarization of the South China Sea, its installation of buoys near the PMZ asserts Chinese authority over a maritime area disputed by South Korea, establishes increased monitoring capabilities along an important maritime throughway, and signals a longer-term effort to expand China's maritime footprint in the Yellow Sea.

Growing Chinese activity in and around the Provisional Measures Zone (PMZ) in the Yellow Sea has become a major source of concern for South Korea over the past year. The PMZ, established by South Korea and China through a 2001 bilateral agreement to temporarily manage their overlapping EEZ claims in the Yellow Sea, allows fishing activities from both sides but does not authorize the installation of other structures.

Although the PMZ has garnered attention in the past year due to multiple standoffs between the Chinese and South Korean coast guards, China has been installing marine observation buoys in and immediately adjacent to the PMZ since 2018.¹ The observation buoys have become a visible part of the public debate over the past year, but their strategic implications remain less well understood than those of the recent standoffs or the larger Chinese platforms. China's use of buoys in maritime disputes was highlighted by its recent installation at Scarborough Shoal, casting new light on the significance of those in the Yellow Sea. China's installation of buoys near the PMZ asserts Chinese authority over a maritime area disputed by South Korea, establishes increased monitoring capabilities along an important maritime throughway, and signals a longer-term effort to expand China's maritime footprint in the Yellow Sea.

Our previous Beyond Parallel report discusses three additional permanent structures in the Yellow Sea: Shen Lan 1 and Shen Lan 2, the two aquaculture cages, and Atlantic Amsterdam, a "central integrated management platform" for operating the cages.² The observation buoys are an additional layer of activity that operates alongside these platforms. Deployed earlier and distributed more widely, the buoys serve as another major element of China's presence in the PMZ.

Chinese Buoys in the Yellow Sea

According to the South Korean Navy Headquarters, South Korea first identified several Chinese marine observation buoys in February 2018, with additional units detected intermittently through May 2023. The presence of thirteen buoys over this period suggests that China deployed them incrementally rather than through a single installation effort. Photographs released by the Navy in June 2025 provided the first public visual confirmation of these buoys and revealed that they vary considerably in shape, size, and structural design.³

Beijing has denied that these buoys serve a political or strategic purpose, claiming they are for maritime meteorological observation.⁴ However, South Korea has expressed serious concern about potential dual-use or military purposes.⁵

The released photographs show several shared characteristics of the buoys, offering insights into their likely capabilities and intended functions. Most appear to be consistent with astandardized Chinese type of 10-meter ocean environmental monitoring buoy, exhibiting a lighthouse-style design, with a circular floating base, central vertical tower, and an upper platform. The tower structure allows for mounting sensors and communication equipment. Also visible on some buoys are the labels "Marine Observation Buoys of P R China" and "Power Construction Corporation of China," the latter being a state-owned enterprise.

Notably, one buoy (#12 in the map below) features a distinctive design with multiple solar panels around the tower. The use of solar arrays indicates that the buoys are intended for long-duration autonomous operation that requires sustained power generation. This indicates that the buoy contains instruments that require consistent energy input, such as environmental sensors, AIS receivers, or communication modules.

Although the physical characteristics visible in the photographs are consistent with China's stated explanation that these are meteorological or ocean observation buoys, photographs alone cannot confirm the full range of their functions. The designs do not reveal any overtly military systems, but they also do not preclude the possibility of dual-use capabilities. However, regardless of the buoys' capabilities, their placement within and adjacent to the PMZ is itself consequential in demonstrating China's strategic intent in the Yellow Sea (West Sea).

The mapped locations of the buoys reveal several notable patterns.

With one exception (buoy #2), all the buoys are deployed both outside the PMZ and on China's side of a theoretical median line drawn between China and South Korea's overlapping EEZ claims. This indicates that Beijing showed consideration for Seoul's likely reaction and mostly sought to avoid the direct provocations of installing the buoys either within the PMZ or over the median line. This, in turn, makes the deployment of buoy #2 and the larger fixed platforms within the PMZ even more noteworthy, given Beijing's apparent awareness that deployment in those areas could trigger a reaction from Seoul.

The clustering of buoys to the south is also noteworthy. Chinese forces deploying from naval bases in Dalian or Qingdao must pass through this area, between Shanghai and Jeju Island, when leaving the Yellow Sea. U.S. or allied naval forces en route to a contingency in the Taiwan Strait or South China Sea would also potentially navigate in the vicinity. The deployment of additional sensing and detection platforms in this area, even if only for weather and environmental monitoring, affords Beijing benefits in protecting its own naval forces and detecting others in this critical location.

Strategic Implications

China's deployments of buoys in the Yellow Sea add yet another layer to its approach toward managing disputes with South Korea while furthering its own maritime interests. Like many of China's maritime activities, the buoys accomplish several things simultaneously: they increase China's monitoring and sensing capabilities in an important maritime area; they assert control over a less sensitive but still disputed portion of overlapping maritime claims; and, importantly in the Yellow Sea context, they test South Korean reactions to inform future deployments. Unlike its buoys in the South China Sea at Scarborough Shoal, which were clearly intended to be noticed, most of China's Yellow Sea buoys were likely deployed with the intention of staying out of the spotlight. But in the wake of tensions between coast guards and consistent public attention in Seoul, Beijing's buoys and other deployments near the PMZ are likely to face only more scrutiny going forward.

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