While the eyes of the world remain fixed on the crisis in the Red Sea, another threat to global stability continues to stir in the South China Sea. In early December, the Chinese Coast Guard rammed and assaulted Philippine supply vessels with water cannons near Second Thomas Shoal, a reef whose sovereignty is disputed between the two nations and lies 121 miles (194 km) west of the Philippines. The reef is home to the BRP Sierra Madre, a US-built Philippine transport ship which the Philippines intentionally ran aground on Second Thomas Shoal in 1999 to further their claim to the area. 

Since its grounding, the ship’s condition has deteriorated significantly and requires frequent resupply and rotation of the small marine detachment that crews it. Beginning in 2014, the Chinese Coast Guard has attempted to blockade the shoal and interfere with Philippine efforts to resupply the Sierra Madre as part of the China’s larger plan to enforce their claims on the area within the “nine-dash line,” an artificial boundary claiming most of the South China Sea to be within the PRC’s sovereignty. Much of this disputed area, including the Paracel and Spratly islands (Second Thomas Shoal lying within the latter) is much closer to the Philippines, Vietnam, Malaysia, and Brunei, than China. 

In 2016, the Permanent Court of Arbitration at the Hague ruled in favor of the Philippines in a dispute over the nine-dash line, declaring the Chinese boundary to be “without lawful effect” and recognizing Second Thomas Shoal and nearby Chinese-occupied Mischief Reef as within the Philippines’ exclusive economic zone, though the Chinese government neither participated in the case nor recognized the ruling. 

In February 2023, Philippine President Ferdinand Marcos Jr. agreed to offer increased US access to Philippine military bases, a move that Chinese officials decried as “[escalating] tension in the region.” Over the following months, Chinese interdiction of the Sierra Madre resupply missions increased in severity, with major confrontations occurring in April, August, October, and November, before the most aforementioned incident in December.

The Sierra Madre saga falls within the realm of the PRC’s several grey zone operations in the Western Pacific. Grey zone operations allow authoritarian powers like China to use a wide array of efforts “from nefarious economic activities, influence operations, and cyberattacks to mercenary operations, assassinations, and disinformation campaigns” as one scholar suggests, to revise the geopolitical status quo short of open war. 

China specifically has used land-reclamation projects, airspace violations, military exercises, and disinformation campaigns to further its goals in the South China Sea and elsewhere through a strategy commonly referred to as “Three Warfares.” Composed of psychological, media, and legal warfare, Three Warfares seeks to be provocative without provoking military responses to its aggression, spin its own narrative of events for domestic and international audiences, and attempt to legally justify its claims.

Against the Philippines, China uses Three Warfares through its heavy-handed Coast Guard operations, harassing Philippine fishing vessels in disputed areas in addition to the blockade of Second Thomas Shoal. When these confrontations inevitably make the news, PRC statements are quick to blame the United States for instability in the South China Sea, a narrative that reaches foreign audiences, such as in the AP’s recent headline “Beijing accuses US of stirring trouble” in their story on the December Sierra Madre incident.

China has also engaged in several land reclamation projects in the South China Sea to deter challenges to their claims. Since 2013, China has expanded seven reefs and islands in the South China Sea. As part of this effort, China has built numerous hangars for aircraft, radar installations, and anti-air weapons systems in several air bases in both the Spratly and Paracel Islands, essentially establishing permanent military bases in areas previously uninhabitable. These operations have strengthened the PRC’s ability to deter other claimants to the South China Sea from challenging Chinese military power in the region. As CSIS fellow Gregory Poling has argued, even against the United States, China “would control the sea and airspace of the South China Sea at the outbreak of hostilities thanks to its artificial island bases.”

In addition to operations in the Spratly and Paracel Islands, China has also applied Three Warfares to its interactions with Taiwan. While Xi Jinping continues to publicly advocate for reunification with Taiwan and argue for PRC sovereignty over the island nation, Chinese military exercises in and near Taiwanese waters have coincided with major meetings between US and Taiwanese officials in 2022 and 2023. As Taiwan nears its next general election on January 13, China has increased its pressure on the country with fresh airspace violations of the median line boundary that traditionally divides the two nations, this time with balloons reminiscent of the 2023 incident over the United States in addition to the customary trespasses by PLA combat aircraft. 

China has also stepped up disinformation efforts regarding Taiwan’s relationship with the United States, spreading online rumors about US-imported poisonous pork and blood harvesting schemes in an effort to sow mistrust of the United States among the Taiwanese people. Though the claims were quickly debunked, they demonstrate the media aspect of Three Warfares, alongside the PRC’s psychologically-targeted military exercises and claims of legal sovereignty over the island.

China’s maritime challenges to its neighbors in 2023 were widespread and varied, ranging from the interference in Vietnam’s exclusive economic zone to Coast Guard patrols around the Senkaku/Diaoyu Islands, and island chain northeast of Taiwan that the PRC, Taiwan, and Japan all claim. The Three Warfares strategy and China’s broader use of grey zone operations isn’t new and the US intelligence community is well aware of them, but whether or not the United States can reclaim the initiative in the South China Sea in 2024 and beyond remains to be seen.

China’s use of grey zone operations also attacks a blind spot in just war theory. The PRC’s aggressive but non-warfighting tactics to gradually reshape the South China Sea require similar demonstrations of military power from the United States without sparking an open conflict, a correction of China’s narrative of legal claims, and strong cooperation with US allies in the region. The United States remains the best guarantor of security and stability in East Asia, a role we must continue both out of national self-interest as well as in defense of a just, rules-based international order that reflects American values.