On April 26, 2025, the Chinese Coast Guard raised the national flag over Sandy Cay, a disputed reef in the Spratly Islands, marking a significant escalation in the South China Sea territorial disputes. This action, reported by China Central Television (CCTV), was accompanied by a declaration of “sovereign jurisdiction” over the reef, located just a few kilometers from Thitu Island, a Philippine-controlled feature. The move asserts a 12-nautical-mile maritime territory that overlaps with the Philippines’ exclusive economic zone (EEZ), intensifying tensions between Beijing and Manila. This development unfolds against the backdrop of the annual Balikatan exercises, the largest joint U.S.-Philippines military drills emphasizing coastal defense and island seizure, conducted in parts of the South China Sea. The timing and location of China’s action underscore its strategic intent to challenge regional claimants and their allies, particularly the United States, which has deepened military cooperation with the Philippines since 2022 under President Ferdinand Marcos Jr. This article examines the geopolitical, economic, and legal dimensions of China’s flag-raising on Sandy Cay, contextualizing it within the broader South China Sea disputes, international maritime law, and the strategic responses of affected states.
Sandy Cay, known as Tiexian Jiao in China and Pagasa Cay 2 in the Philippines, is a low-tide elevation in the Spratly Islands, a sprawling archipelago of reefs, atolls, and islands contested by China, the Philippines, Vietnam, Malaysia, Taiwan, and Brunei. The reef’s proximity to Thitu Island, where the Philippine Coast Guard has maintained a presence since 2023 to monitor Chinese activities, places it at the heart of overlapping territorial claims. According to the Financial Times, China’s claim to Sandy Cay effectively extends its maritime jurisdiction into waters claimed by the Philippines, challenging Manila’s rights under the United Nations Convention on the Law of the Sea (UNCLOS). The 2016 Permanent Court of Arbitration (PCA) ruling in the Philippines v. China case explicitly rejected China’s expansive “nine-dash line” claim, affirming that features like Sandy Cay, which are submerged at high tide, cannot generate territorial seas or EEZs unless they are within 12 nautical miles of a naturally formed island. China’s rejection of the PCA ruling and its physical assertion of control over Sandy Cay illustrate a strategy of incremental expansion, leveraging coast guard operations to establish de facto control without direct military confrontation.
The South China Sea is a critical global waterway, with an estimated $3.4 trillion in trade passing through annually, according to a 2017 study by the Center for Strategic and International Studies (CSIS). The region is also rich in fisheries and potential hydrocarbon reserves, though estimates of oil and gas deposits vary. The U.S. Energy Information Administration (EIA) in 2013 suggested that the South China Sea contains approximately 11 billion barrels of oil and 190 trillion cubic feet of natural gas, primarily near undisputed shorelines. However, the strategic value of the Spratly Islands lies not only in resources but also in their position along vital sea lines of communication (SLOCs). China’s construction of artificial islands, such as Subi Reef near Sandy Cay, equipped with airstrips, naval facilities, and radar systems, enhances its ability to project power and monitor regional activities. The Asia Maritime Transparency Initiative (AMTI) reported in 2023 that China has reclaimed over 3,200 acres of land in the Spratlys, far surpassing Vietnam’s 2,300 acres and the smaller reclamations by Malaysia and the Philippines.
China’s flag-raising on Sandy Cay must be understood within the historical context of its maritime ambitions. Chinese historical records, such as the Yi Wu Zhi from the Eastern Han Dynasty and Dao Yi Zhi Lüe from the Yuan Dynasty, document early Chinese exploration of the South China Sea, referring to features like the Spratlys as “Qianlishitang” (thousand-li rocky reefs). The 1935 Map of the South China Sea Islands published by China’s Committee for the Examination for Land and Sea Maps formalized names for 132 features, including Sandy Cay. Beijing cites these records to assert “historical rights” predating modern international law. However, the 2016 PCA ruling clarified that historical usage does not confer sovereignty under UNCLOS, which prioritizes coastal state rights within 200 nautical miles of their baselines. China’s claim to Sandy Cay, therefore, relies on a narrative of continuous occupation and administration, bolstered by physical presence rather than legal recognition.
The Philippines’ response to China’s action has been shaped by its strengthened alliance with the United States. The revitalization of the Enhanced Defense Cooperation Agreement (EDCA) in February 2023 granted the U.S. access to nine Philippine military bases, including sites in Palawan near the Spratlys. This agreement, coupled with the Balikatan exercises, signals a robust deterrent posture. The exercises, which began in 1991 but expanded significantly under Marcos, involved over 16,000 troops in 2024, focusing on maritime security and amphibious operations. The U.S. Indo-Pacific Command reported that the 2025 drills included scenarios simulating island recapture, directly relevant to disputes like Sandy Cay. The Philippines has also bolstered its coast guard presence, with vessels like the BRP Teresa Magbanua stationed at nearby Sabina Shoal to counter Chinese activities. However, incidents of Chinese coast guard vessels using water cannons and ramming Philippine ships, as documented by the Philippine Coast Guard in 2024, highlight the asymmetry in maritime capabilities.
Vietnam, another major claimant in the Spratlys, has also escalated its activities in response to China’s assertiveness. AMTI satellite imagery from March 2025 revealed Vietnam’s reclamation of 641 acres across features like Pearson and Ladd Reefs, aiming to match China’s infrastructure development. Vietnam’s historical claims, rooted in its occupation of 29 Spratly features since the 1970s, were formalized in the 2012 Vietnamese Law of the Sea. The 1988 Johnson Reef clash, where China sank three Vietnamese vessels, remains a stark reminder of Hanoi’s resolve to defend its interests. Vietnam’s diplomatic protests, lodged through ASEAN channels, emphasize adherence to UNCLOS and the 2002 Declaration on the Conduct of Parties in the South China Sea (DOC), though negotiations for a binding Code of Conduct (COC) remain stalled, as noted in the 2024 ASEAN Summit communique.
Malaysia and Brunei, with smaller claims, have adopted more restrained approaches. Malaysia controls five Spratly features and has developed Swallow Reef into a naval outpost, while Brunei claims Louisa Reef within its EEZ. Both countries have prioritized diplomacy, with Malaysia advocating for joint resource exploration under the DOC. The Malaysian Ministry of Foreign Affairs in 2024 reiterated its commitment to UNCLOS, but avoided direct confrontation with China, reflecting its economic dependence on Beijing. Brunei, similarly, has pursued quiet diplomacy, focusing on maritime boundary negotiations with neighbors like Indonesia, finalized in 2022 after 12 years of talks, as reported by the Indonesian Ministry of Foreign Affairs.
The international community’s response to China’s actions on Sandy Cay reflects broader geopolitical alignments. The United States, while not a claimant, has intensified Freedom of Navigation Operations (FONOPs) to challenge China’s claims. The U.S. Navy’s 7th Fleet conducted 10 FONOPs in 2024, including transits near Subi Reef, prompting Chinese accusations of “trespassing.” The U.S. State Department’s 2025 statement reaffirmed support for the 2016 PCA ruling and condemned China’s “coercive tactics.” Japan, Australia, and the European Union have also voiced concerns, with Japan providing patrol vessels to the Philippines and Vietnam to enhance maritime security, as noted in a 2023 Japanese Ministry of Defense report. The Group of Seven (G7) in 2024 criticized China’s “dangerous incursions,” citing incidents at Second Thomas Shoal and Sabina Shoal.
China’s strategy on Sandy Cay exemplifies its use of “gray zone” tactics—coercive actions short of war—to alter the regional status quo. The China Coast Guard, with over 130 vessels, including the 12,000-ton “Monster” deployed at Sabina Shoal, plays a central role. The 2021 Coast Guard Law authorizes the use of force to enforce maritime claims, raising concerns about escalation, as analyzed by the Sasakawa Peace Foundation. The presence of China’s maritime militia, embedded within its fishing fleet, further complicates responses, as these vessels operate under plausible deniability. A 2023 Stanford University SeaLight project report described “rafting” tactics, where militia boats tie together to form semi-permanent outposts, as seen at Whitsun Reef in 2021.
The legal implications of China’s actions are profound. UNCLOS Article 13 stipulates that low-tide elevations like Sandy Cay cannot generate territorial seas unless within 12 nautical miles of a high-tide feature. Thitu Island, a naturally formed island under Philippine control, generates such a zone, but China’s artificial enhancements on nearby Subi Reef do not, per the PCA ruling. China’s claim to “sovereign jurisdiction” thus lacks legal grounding, relying instead on physical control and historical assertions. The Philippines has leveraged international law to bolster its position, with President Marcos emphasizing ASEAN centrality and UNCLOS at the 2024 Shangri-La Dialogue. However, China’s non-compliance with the PCA ruling and its veto power in the UN Security Council limit legal recourse.
Economically, the South China Sea disputes threaten regional stability. The World Bank in 2024 estimated that ASEAN economies, heavily reliant on maritime trade, could lose up to 5% of GDP annually from disruptions to SLOCs. The Philippines, with 40% of its fish catch sourced from the West Philippine Sea, faces direct economic losses from Chinese incursions, as reported by the Philippine Bureau of Fisheries and Aquatic Resources. China’s fishing fleets, numbering over 200,000 vessels, have depleted stocks, prompting protests from Vietnam and Indonesia, whose EEZs are also affected. The International Energy Agency (IEA) notes that while hydrocarbon exploration in disputed areas remains limited due to legal uncertainties, joint ventures, such as Malaysia’s with Shell off Borneo, underscore the region’s potential.
Geopolitically, China’s actions on Sandy Cay signal a broader challenge to the U.S.-led regional order. The U.S.-Philippines Mutual Defense Treaty (1951) obligates Washington to defend Manila in case of an armed attack, raising the risk of escalation. A 2023 RAND Corporation study warned that miscalculations in gray zone confrontations could trigger broader conflict, given the U.S.’s treaty obligations and China’s growing naval capabilities. The People’s Liberation Army Navy (PLAN) operates over 370 ships, compared to the U.S. Navy’s 290, per the International Institute for Strategic Studies (IISS) 2024 report. China’s deployment of advanced systems, such as YJ-12 anti-ship missiles on Spratly outposts, enhances its anti-access/area denial (A2/AD) capabilities, complicating U.S. intervention.
ASEAN’s fragmented response further complicates resolution. While the Philippines and Vietnam advocate for a binding COC, China’s economic influence over Laos, Cambodia, and Myanmar delays progress. The 2024 ASEAN Foreign Ministers’ Meeting reiterated calls for “self-restraint,” but lacked enforceable mechanisms, as noted in the joint communique. Indonesia, maintaining neutrality, has strengthened its maritime defenses around the Natuna Islands, where Chinese vessels encroached in 2020, prompting a naval standoff, according to the Indonesian Ministry of Defense.
The environmental impact of reclamation activities also warrants attention. A 2024 UN Environment Programme (UNEP) report documented severe coral reef damage from China’s dredging, with 70% of Spratly reefs degraded, threatening marine biodiversity and fisheries. Vietnam’s reclamation, while smaller, contributes to similar ecological harm. The Philippines has raised these concerns at ASEAN forums, advocating for environmental cooperation, but China’s focus on sovereignty precludes multilateral agreements.
China’s flag-raising on Sandy Cay is a calculated move to assert dominance in the South China Sea, leveraging coast guard and militia operations to avoid outright conflict while challenging international law. The Philippines, backed by the U.S. and regional partners, faces a delicate balance between deterrence and de-escalation. Vietnam’s parallel escalation and ASEAN’s limited cohesion underscore the complexity of resolving the dispute. Legally, UNCLOS and the PCA ruling provide a framework for contesting China’s claims, but enforcement remains elusive. Economically and environmentally, the stakes are high, with global trade, regional livelihoods, and marine ecosystems at risk. As tensions mount, the international community must prioritize diplomatic channels, such as a COC, to prevent miscalculations that could destabilize the Indo-Pacific.
China’s Assertion of Sovereignty over Sandy Cay Reef: Geopolitical Implications and International Legal Dimensions in the South China Sea Dispute
On April 26, 2025, the Chinese Coast Guard raised the national flag over Sandy Cay, a disputed reef in the Spratly Islands, marking a significant escalation in the South China Sea territorial disputes. This action, reported by China Central Television (CCTV), was accompanied by a declaration of “sovereign jurisdiction” over the reef, located just a few kilometers from Thitu Island, a Philippine-controlled feature. The move asserts a 12-nautical-mile maritime territory that overlaps with the Philippines’ exclusive economic zone (EEZ), intensifying tensions between Beijing and Manila. This development unfolds against the backdrop of the annual Balikatan exercises, the largest joint U.S.-Philippines military drills emphasizing coastal defense and island seizure, conducted in parts of the South China Sea. The timing and location of China’s action underscore its strategic intent to challenge regional claimants and their allies, particularly the United States, which has deepened military cooperation with the Philippines since 2022 under President Ferdinand Marcos Jr. This article examines the geopolitical, economic, and legal dimensions of China’s flag-raising on Sandy Cay, contextualizing it within the broader South China Sea disputes, international maritime law, and the strategic responses of affected states.
Sandy Cay, known as Tiexian Jiao in China and Pagasa Cay 2 in the Philippines, is a low-tide elevation in the Spratly Islands, a sprawling archipelago of reefs, atolls, and islands contested by China, the Philippines, Vietnam, Malaysia, Taiwan, and Brunei. The reef’s proximity to Thitu Island, where the Philippine Coast Guard has maintained a presence since 2023 to monitor Chinese activities, places it at the heart of overlapping territorial claims. According to the Financial Times, China’s claim to Sandy Cay effectively extends its maritime jurisdiction into waters claimed by the Philippines, challenging Manila’s rights under the United Nations Convention on the Law of the Sea (UNCLOS). The 2016 Permanent Court of Arbitration (PCA) ruling in the Philippines v. China case explicitly rejected China’s expansive “nine-dash line” claim, affirming that features like Sandy Cay, which are submerged at high tide, cannot generate territorial seas or EEZs unless they are within 12 nautical miles of a naturally formed island. China’s rejection of the PCA ruling and its physical assertion of control over Sandy Cay illustrate a strategy of incremental expansion, leveraging coast guard operations to establish de facto control without direct military confrontation.
The South China Sea is a critical global waterway, with an estimated $3.4 trillion in trade passing through annually, according to a 2017 study by the Center for Strategic and International Studies (CSIS). The region is also rich in fisheries and potential hydrocarbon reserves, though estimates of oil and gas deposits vary. The U.S. Energy Information Administration (EIA) in 2013 suggested that the South China Sea contains approximately 11 billion barrels of oil and 190 trillion cubic feet of natural gas, primarily near undisputed shorelines. However, the strategic value of the Spratly Islands lies not only in resources but also in their position along vital sea lines of communication (SLOCs). China’s construction of artificial islands, such as Subi Reef near Sandy Cay, equipped with airstrips, naval facilities, and radar systems, enhances its ability to project power and monitor regional activities. The Asia Maritime Transparency Initiative (AMTI) reported in 2023 that China has reclaimed over 3,200 acres of land in the Spratlys, far surpassing Vietnam’s 2,300 acres and the smaller reclamations by Malaysia and the Philippines.
China’s flag-raising on Sandy Cay must be understood within the historical context of its maritime ambitions. Chinese historical records, such as the Yi Wu Zhi from the Eastern Han Dynasty and Dao Yi Zhi Lüe from the Yuan Dynasty, document early Chinese exploration of the South China Sea, referring to features like the Spratlys as “Qianlishitang” (thousand-li rocky reefs). The 1935 Map of the South China Sea Islands published by China’s Committee for the Examination for Land and Sea Maps formalized names for 132 features, including Sandy Cay. Beijing cites these records to assert “historical rights” predating modern international law. However, the 2016 PCA ruling clarified that historical usage does not confer sovereignty under UNCLOS, which prioritizes coastal state rights within 200 nautical miles of their baselines. China’s claim to Sandy Cay, therefore, relies on a narrative of continuous occupation and administration, bolstered by physical presence rather than legal recognition.
The Philippines’ response to China’s action has been shaped by its strengthened alliance with the United States. The revitalization of the Enhanced Defense Cooperation Agreement (EDCA) in February 2023 granted the U.S. access to nine Philippine military bases, including sites in Palawan near the Spratlys. This agreement, coupled with the Balikatan exercises, signals a robust deterrent posture. The exercises, which began in 1991 but expanded significantly under Marcos, involved over 16,000 troops in 2024, focusing on maritime security and amphibious operations. The U.S. Indo-Pacific Command reported that the 2025 drills included scenarios simulating island recapture, directly relevant to disputes like Sandy Cay. The Philippines has also bolstered its coast guard presence, with vessels like the BRP Teresa Magbanua stationed at nearby Sabina Shoal to counter Chinese activities. However, incidents of Chinese coast guard vessels using water cannons and ramming Philippine ships, as documented by the Philippine Coast Guard in 2024, highlight the asymmetry in maritime capabilities.
Vietnam, another major claimant in the Spratlys, has also escalated its activities in response to China’s assertiveness. AMTI satellite imagery from March 2025 revealed Vietnam’s reclamation of 641 acres across features like Pearson and Ladd Reefs, aiming to match China’s infrastructure development. Vietnam’s historical claims, rooted in its occupation of 29 Spratly features since the 1970s, were formalized in the 2012 Vietnamese Law of the Sea. The 1988 Johnson Reef clash, where China sank three Vietnamese vessels, remains a stark reminder of Hanoi’s resolve to defend its interests. Vietnam’s diplomatic protests, lodged through ASEAN channels, emphasize adherence to UNCLOS and the 2002 Declaration on the Conduct of Parties in the South China Sea (DOC), though negotiations for a binding Code of Conduct (COC) remain stalled, as noted in the 2024 ASEAN Summit communique.
Malaysia and Brunei, with smaller claims, have adopted more restrained approaches. Malaysia controls five Spratly features and has developed Swallow Reef into a naval outpost, while Brunei claims Louisa Reef within its EEZ. Both countries have prioritized diplomacy, with Malaysia advocating for joint resource exploration under the DOC. The Malaysian Ministry of Foreign Affairs in 2024 reiterated its commitment to UNCLOS, but avoided direct confrontation with China, reflecting its economic dependence on Beijing. Brunei, similarly, has pursued quiet diplomacy, focusing on maritime boundary negotiations with neighbors like Indonesia, finalized in 2022 after 12 years of talks, as reported by the Indonesian Ministry of Foreign Affairs.
The international community’s response to China’s actions on Sandy Cay reflects broader geopolitical alignments. The United States, while not a claimant, has intensified Freedom of Navigation Operations (FONOPs) to challenge China’s claims. The U.S. Navy’s 7th Fleet conducted 10 FONOPs in 2024, including transits near Subi Reef, prompting Chinese accusations of “trespassing.” The U.S. State Department’s 2025 statement reaffirmed support for the 2016 PCA ruling and condemned China’s “coercive tactics.” Japan, Australia, and the European Union have also voiced concerns, with Japan providing patrol vessels to the Philippines and Vietnam to enhance maritime security, as noted in a 2023 Japanese Ministry of Defense report. The Group of Seven (G7) in 2024 criticized China’s “dangerous incursions,” citing incidents at Second Thomas Shoal and Sabina Shoal.
China’s strategy on Sandy Cay exemplifies its use of “gray zone” tactics—coercive actions short of war—to alter the regional status quo. The China Coast Guard, with over 130 vessels, including the 12,000-ton “Monster” deployed at Sabina Shoal, plays a central role. The 2021 Coast Guard Law authorizes the use of force to enforce maritime claims, raising concerns about escalation, as analyzed by the Sasakawa Peace Foundation. The presence of China’s maritime militia, embedded within its fishing fleet, further complicates responses, as these vessels operate under plausible deniability. A 2023 Stanford University SeaLight project report described “rafting” tactics, where militia boats tie together to form semi-permanent outposts, as seen at Whitsun Reef in 2021.
The legal implications of China’s actions are profound. UNCLOS Article 13 stipulates that low-tide elevations like Sandy Cay cannot generate territorial seas unless within 12 nautical miles of a high-tide feature. Thitu Island, a naturally formed island under Philippine control, generates such a zone, but China’s artificial enhancements on nearby Subi Reef do not, per the PCA ruling. China’s claim to “sovereign jurisdiction” thus lacks legal grounding, relying instead on physical control and historical assertions. The Philippines has leveraged international law to bolster its position, with President Marcos emphasizing ASEAN centrality and UNCLOS at the 2024 Shangri-La Dialogue. However, China’s non-compliance with the PCA ruling and its veto power in the UN Security Council limit legal recourse.
Economically, the South China Sea disputes threaten regional stability. The World Bank in 2024 estimated that ASEAN economies, heavily reliant on maritime trade, could lose up to 5% of GDP annually from disruptions to SLOCs. The Philippines, with 40% of its fish catch sourced from the West Philippine Sea, faces direct economic losses from Chinese incursions, as reported by the Philippine Bureau of Fisheries and Aquatic Resources. China’s fishing fleets, numbering over 200,000 vessels, have depleted stocks, prompting protests from Vietnam and Indonesia, whose EEZs are also affected. The International Energy Agency (IEA) notes that while hydrocarbon exploration in disputed areas remains limited due to legal uncertainties, joint ventures, such as Malaysia’s with Shell off Borneo, underscore the region’s potential.
Geopolitically, China’s actions on Sandy Cay signal a broader challenge to the U.S.-led regional order. The U.S.-Philippines Mutual Defense Treaty (1951) obligates Washington to defend Manila in case of an armed attack, raising the risk of escalation. A 2023 RAND Corporation study warned that miscalculations in gray zone confrontations could trigger broader conflict, given the U.S.’s treaty obligations and China’s growing naval capabilities. The People’s Liberation Army Navy (PLAN) operates over 370 ships, compared to the U.S. Navy’s 290, per the International Institute for Strategic Studies (IISS) 2024 report. China’s deployment of advanced systems, such as YJ-12 anti-ship missiles on Spratly outposts, enhances its anti-access/area denial (A2/AD) capabilities, complicating U.S. intervention.
ASEAN’s fragmented response further complicates resolution. While the Philippines and Vietnam advocate for a binding COC, China’s economic influence over Laos, Cambodia, and Myanmar delays progress. The 2024 ASEAN Foreign Ministers’ Meeting reiterated calls for “self-restraint,” but lacked enforceable mechanisms, as noted in the joint communique. Indonesia, maintaining neutrality, has strengthened its maritime defenses around the Natuna Islands, where Chinese vessels encroached in 2020, prompting a naval standoff, according to the Indonesian Ministry of Defense.
The environmental impact of reclamation activities also warrants attention. A 2024 UN Environment Programme (UNEP) report documented severe coral reef damage from China’s dredging, with 70% of Spratly reefs degraded, threatening marine biodiversity and fisheries. Vietnam’s reclamation, while smaller, contributes to similar ecological harm. The Philippines has raised these concerns at ASEAN forums, advocating for environmental cooperation, but China’s focus on sovereignty precludes multilateral agreements.
China’s flag-raising on Sandy Cay is a calculated move to assert dominance in the South China Sea, leveraging coast guard and militia operations to avoid outright conflict while challenging international law. The Philippines, backed by the U.S. and regional partners, faces a delicate balance between deterrence and de-escalation. Vietnam’s parallel escalation and ASEAN’s limited cohesion underscore the complexity of resolving the dispute. Legally, UNCLOS and the PCA ruling provide a framework for contesting China’s claims, but enforcement remains elusive. Economically and environmentally, the stakes are high, with global trade, regional livelihoods, and marine ecosystems at risk. As tensions mount, the international community must prioritize diplomatic channels, such as a COC, to prevent miscalculations that could destabilize the Indo-Pacific.
