On the latest episode of The President’s Inbox, Jim sat down with Derek Grossman, senior defense analyst at RAND and professor of policy analysis at the RAND School of Public Policy, to discuss the confrontations between China and the Philippines over their competing claims in the South China Sea and the consequences for the United States.

Here are three takeaways from their conversation:

1) The South China Sea holds strategic significance for both China and the Philippines and shapes the broader balance of power in the Western Pacific. The South China Sea lies at the crossroads of major shipping lanes vital to the maritime trade of China, Taiwan, Vietnam, and other Asian economies. It also holds rich fishing grounds, oil and gas reserves, and deep-sea mineral deposits of nickel, cobalt, and lithium. Many of these resources fall within the Philippines’ legally recognized Exclusive Economic Zone (EEZ) and are essential for its food security and industrial development. China claims the waters based on historical fishing activity and the “nine-dash line” drawn from Ming and Qing dynasty-era maps. Over the past decade, China has constructed dozens of artificial islands in contested areas of the Spratly and Paracel chains, equipping them with airfields, depots, and naval bases. Derek noted that “Right now, China wants to use these bases to intimidate regional neighbors on trade issues, but they would also  become big military advantages in the case of a conflict with Taiwan, the Philippines, or the United States.” The Philippines has sought to secure international support for its EEZ, and in 2016 it secured a legal victory at the Permanent Court on Arbitration in 2016 against the Chinese territorial claims. However, despite both China and the Philippines being party to the United Nations Convention on the Law of the Sea (UNCLOS), China has refused to accept the 2016 ruling and continues to claim most of the South China Sea.

2) China is employing gray-zone tactics to secure the contested waters.  In 1999, the Philippines deliberately grounded the World War II-era transport ship Sierra Madre at Second Thomas Shoal to reinforce its legal claim to the feature. Despite the ship’s severe deterioration, Filipino marines continue to garrison it, sustained by regular supply missions. These missions face frequent harassment from the China Coast Guard (CCG), which has expanded operations in the region under the pretext of protecting Chinese fishermen. In reality, however, the CCG asserts territorial control and supports China’s artificial islands and expanding military bases. Derek explained that the CCG’s “harassment consists of firing water cannons, ramming their ships, blinding assets with military-grade lasers.” In response, the Philippine Navy has invited foreign journalists on missions and released video evidence of the confrontations. Armed naval escorts have also become more frequent. A limited July 2024 agreement, which required Manila to provide twenty-four-hour notice for resupply missions and avoid structural reinforcements, briefly reduced tensions at Second Thomas Shoal. Nonetheless, clashes continue elsewhere in the South China Sea.

3) Rising Chinese-Philippine tensions are raising the risk of a U.S.-China confrontation. China’s superiority in vessels, maritime technology, and material resources has steadily strengthened its position in the South China Sea. In response, Manila has sought to deepen its security partnerships with other nations seeking to deter Chinese aggression such as Australia, Japan, and New Zealand. But central to the Philippine’s security strategy is its 1951 Mutual Defense Treaty with the United States. In recent years, domestic politics have pushed Manila closer to Washington. Former President Rodrigo Duterte’s pivot toward China failed to deliver promised Belt and Road investments or joint energy projects, triggering a backlash from the Philippines’s strongly-pro American public and military. Under President Bongbong Marcos, elected in 2022, the Philippines has revived its alliance with the United States, granting access to nine military bases under the Enhanced Defense Cooperation Agreement and launching the Archipelagic Defense Concept to shift military focus from internal threats to maritime defense. Derek noted: “China is testing whether the United States is really willing to support the Philippines.” The CCG has taken advantage of ambiguities in the 1951 Treaty by intentionally keeping its harassment of Filipino vessels in contested areas to non-lethal tactics. The clashes bring with them the risk of an incident that would trigger treaty obligations and compel the United States to intervene. Yet without U.S. action or stronger Filipino deterrence, China’s encroaching control of the South China Sea will allow it to dominate vital trade routes, project military power, and pressure neutral neighbors. If taken to its conclusion, this will gradually sideline Manila, and by extension, Washington, from this strategic region. 

If you’re looking to learn more from Derek, check out is recent pieces for RAND such as “The Philippines Is Ever More Focused on Taiwan,” and “The Chinese Communist Party's Gray Zone Tactics Against Taiwan.”