Chinese naval operations in the Yellow Sea, known in Korea as the West Sea, have grown markedly more aggressive in recent years, with a sharp uptick in activity within South Korea’s Exclusive Economic Zone (EEZ). These incursions, paired with the construction of permanent maritime structures, have raised growing concern in Seoul over Beijing’s intentions and the long-term implications for regional stability and South Korea’s sovereignty.
The number of unauthorized Chinese naval entries into South Korea’s EEZ has surged. According to local media reports, Chinese warships crossed into South Korean waters more than 330 times in 2024 – almost daily. That figure represents a threefold increase compared to the 110 such incidents recorded in 2017. The frequency has risen steadily in the years since, with 230 incidents recorded in 2018 and 290 in 2019. After a relative plateau between 2020 and 2022, when annual entries hovered around 200, the figure jumped to 360 in 2023. By mid-April 2025, the count had already exceeded 100, indicating an even steeper trajectory this year.
While international law allows for the free movement of naval vessels in another state’s EEZ, so long as the transiting vessels “exercise due regard to the rights and duties of the coastal State,” China itself frequently protests such operations. Its naval movements in South Korea’s EEZ suggest that Beijing applies a different standard to its own actions.
Some of these movements took place in the Provisional Measures Zone (PMZ), an area of overlapping EEZ claims between South Korea and China. However, a significant number occurred in waters internationally recognized as being under full South Korean jurisdiction. These patterns suggest a shift from ambiguous probing to deliberate incursions.
Much of the naval activity can be traced to China’s North Sea Fleet, based in Qingdao. The vessels involved include destroyers, frigates, and increasingly, submarines, demonstrating a willingness to project underwater capabilities as well. Analysts say these deployments reflect a strategic effort by Beijing to expand its reach beyond disputed zones and test South Korea’s operational limits.
At the same time, China has begun constructing permanent installations in the disputed area of the Yellow Sea, which it labels fish farms. South Korean officials believe the structures – such as ShenLan No. 1 and No. 2 – not only serve civilian functions but also advance Beijing’s maritime claims. These installations raise red flags in Seoul, where they are widely viewed as tools of incremental encroachment.
West Sea: The Next Strategic Flashpoint
Unlike the South China Sea, there is no territory in dispute between China and South Korea. Instead, the maritime dispute centers on the exact demarcation of each country’s EEZ. Yet the tactics China is employing in the West Sea mirror its well-documented playbook in the South China Sea: escalate gradually, install fixed structures, issue unilateral maritime claims, and shift the status quo by establishing a permanent presence.
One particularly aggressive move has been China’s insistence that South Korea refrain from conducting any operations west of the 124th meridian east – an arbitrary demarcation that slices into South Korean waters without legal basis under international law.
This line has become a de facto red zone. As early as 2013, Beijing warned Seoul not to cross it. What began as rhetorical signaling has now evolved into a pattern of assertive physical actions, including Chinese naval drills and deployments of surveillance and logistical platforms. The implication is clear: Beijing intends to solidify its presence and redefine maritime boundaries through continuous pressure and physical occupation.
The strategic significance of the West Sea cannot be overstated. For South Korea, it abuts critical military and commercial infrastructure, including the Second Fleet Command and Camp Humphreys – the largest U.S. military base outside the United States. For China, the Yellow Sea serves as both a maritime gateway and a potential fallback buffer in the event of conflict in the Taiwan Strait. This is not a peripheral theater for the People’s Liberation Army Navy; it is now considered integral to Beijing’s broader security calculus.
Chinese warships have approached within 40 kilometers of Baengnyeong – within South Korea’s contiguous zone, and disturbingly close to populated and militarized South Korean territory. In Seoul, such actions are not interpreted as navigational mistakes but as calibrated demonstrations of strength. For South Korean officials, these developments underscore a sobering new reality: the era of a more restrained Chinese navy is over.
Unchecked, China’s behavior threatens to erode South Korea’s operational sovereignty in its own EEZ, destabilize regional norms, and embolden other countries to pursue similar unilateral claims. It could also undermine freedom of navigation, an issue of growing concern for all Indo-Pacific states.
In the context of heightened cross-strait tensions, the West Sea may also become a secondary front in any Taiwan-related conflict. Chinese strategy appears increasingly geared toward securing a multilayered maritime buffer, stretching from the South China Sea to the East China Sea, and now up to the Yellow Sea. This regionalization of China’s maritime assertiveness has major implications for Northeast Asia’s security landscape.
Seoul’s Evolving Response
In response to China’s activities, South Korea has adopted a cautious but increasingly robust strategy. The government recently installed a floating platform to monitor the West Sea and gather environmental and maritime data. More importantly, the Republic of Korea Navy (ROKN) is tracking Chinese movements with increased vigilance, issuing radio warnings and strengthening surveillance near key islands like Baengnyeong and Yeonpyeong.
South Korea has also utilized diplomatic channels and pursued dialogue aimed at reducing tensions. But official responses have remained muted, reflecting a reluctance to provoke China amid sensitive political and economic dynamics.
Still, growing public frustration and security concerns may force Seoul to go further. According to defense insiders, the government is weighing the deployment of its own marine research platforms in the PMZ – a move that would mirror China’s fish farm strategy and reassert South Korean claims.
Experts argue that South Korea needs to shift from symbolic gestures to a comprehensive response. This would include publicly rejecting China’s claims along the 124th meridian east as baseless under the United Nations Convention on the Law of the Sea (UNCLOS), strengthening legal arguments through international fora, and raising the issue in global diplomatic platforms.
Militarily, Seoul may need to enhance its underwater surveillance network, expand patrol capabilities, and modernize early-warning systems in the Yellow Sea. Importantly, this will require sustained investment and support from like-minded regional partners.
Given the growing strength of China’s navy, South Korea may not be able to address the challenge alone. Coordinated efforts with regional countries facing similar maritime pressure – including Japan, Vietnam, the Philippines, and India – could prove essential. Potential avenues include a multilateral maritime code of conduct, joint patrols, and intelligence sharing. By working together, these countries can present a credible alternative to Beijing’s unilateralism and prevent China from exploiting the divisions among them.
So far, South Korea has leaned on quiet diplomacy rather than public confrontation. But as Chinese incursions intensify and regional unease deepens, the moment may have arrived to internationalize the issue. Framing the West Sea as a new front in Beijing’s broader maritime strategy could reshape the conversation and rally broader support for upholding rules-based order in Asia’s waters.
A Turning Point – and a Test for China
This naval standoff comes at a pivotal moment, as South Korea approaches a political transition. Former President Yoon Suk-yeol, widely seen as aligned with the United States and hardline on China, was impeached in April and a presidential election on June 3 will determine his successor.
The heavy favorite in that race is Lee Jae-myung of the opposition, who has signaled a more pragmatic and balanced approach to foreign policy, particularly toward Beijing. For China, this presents a rare golden opportunity to recalibrate its relationship with Seoul.
A more restrained Chinese posture in the West Sea, supported by sustained dialogue and confidence-building measures, could unlock new avenues of cooperation with South Korea – not only in diplomacy but also in trade, investment, and regional development. Such a shift could help stabilize the broader security environment and set the stage for more constructive engagement between the two countries.
By ending its maritime provocations and rebuilding trust with South Korea, China could lay the groundwork for a broader, more inclusive regional framework – one that includes South Korea, Japan, India, ASEAN, Russia, and even North Korea – committed to peace, prosperity, and shared responsibility.
However, if Beijing misreads the significance of South Korea’s evolving political landscape and doubles down on coercive tactics, it risks further eroding trust and accelerating the emergence of counterbalancing coalitions. The costs of continued aggression would not be limited to Seoul; they would echo across the region.
To many in South Korea, China’s behavior in the West Sea appears to be part of a long-term strategy to dominate regional waters and undermine neighboring sovereignty. What was once a maritime buffer zone is fast becoming a contested flashpoint. If left unchecked, this creeping militarization could reshape the strategic order of Northeast Asia and threaten decades of maritime stability.
Ultimately, the direction of East Asian security hinges on the choices made now – by both Seoul and Beijing. China’s next move will determine whether the region enters a new phase of engagement or confrontation.