South China Sea Tensions Escalate Amid Intensified Maritime Activities
In 2025, the South China Sea witnessed heightened confrontations and militarization, complicating efforts toward an ASEAN–China Code of Conduct.
In 2025, the South China Sea experienced increased confrontations and militarization, complicating efforts toward an ASEAN–China Code of Conduct (COC). China intensified its maritime activities, with the China Coast Guard (CCG) conducting 134 patrols around Diaoyu Dao, totaling 357 days in 2025. The CCG also maintained a near year-round presence at Scarborough Shoal, with patrols observed on 352 days.
Incidents included the CCG's use of high-pressure water cannons against Filipino fishing vessels near Thitu Island and Sabina Shoal. Additionally, the CCG deployed armed small boats to Second Thomas Shoal, reinforcing its presence in the area.
Militarization efforts saw Vietnam enhancing infrastructure on 21 features in the Spratly Islands, including military barracks and a 3.2-kilometer runway on Barque Canada Reef. China commenced dredging and landfill activities at Antelope Reef in the Paracel Islands, aiming to expand its military capabilities.
The United States increased military engagement with the Philippines, conducting multiple maritime exercises and deploying coastal defense missiles during joint drills. In response, the People's Liberation Army Navy dispatched aircraft carriers to the South China Sea and conducted live-fire exercises near Scarborough Shoal.
Progress toward an ASEAN–China COC continued, with Malaysia hosting five Joint Working Group meetings. By year's end, Malaysia's foreign minister announced that negotiations had made significant progress, with nearly 70% of the content agreed upon. However, contentious issues such as geographic scope, legal status, self-restraint, and the role of outside powers remain unresolved.
Looking ahead, China is expected to leverage U.S. military commitments elsewhere to press its claims in the South China Sea, potentially deploying carrier strike groups to demonstrate its reach. Vietnam is likely to complete its infrastructure program in the Spratlys, increasing its presence in the region. As the 2026 ASEAN Chair, the Philippines may push for a conclusion on the COC, but negotiations are anticipated to be challenging due to differing positions among stakeholders.