Territorial Disputes in the South China Sea
China’s assertiveness in the South China Sea has steadily increased, resulting in heightened tensions with Southeast Asian claimant states, particularly the Philippines, at the Second Thomas Shoal in the Spratly Islands.
Background
China’s sweeping claims of sovereignty over the sea—and the sea’s estimated 11 billion barrels of untapped oil and 190 trillion cubic feet of natural gas—have antagonized competing claimants Brunei, Indonesia, Malaysia, the Philippines, Taiwan, and Vietnam. As early as the 1970s, countries began to claim islands and various zones in the South China Sea, such as the Spratly Islands, which possess rich natural resources and fishing areas. The failure of Chinese and Southeast Asian leaders to resolve the disputes diplomatically could undermine international laws governing maritime disputes and encourage destabilizing arms buildups.
China maintains [PDF] that, under international law, foreign militaries cannot conduct intelligence-gathering activities, such as reconnaissance flights, in its exclusive economic zone (EEZ). According to the United States, claimant countries, under the UN Convention of the Law of the Sea (UNCLOS), should have freedom of navigation through EEZs in the sea and are not required to notify claimants of military activities. In July 2016, the Permanent Court of Arbitration at The Hague ruled on a claim brought against China by the Philippines under UNCLOS, ruling in favor of the Philippines on almost every count. While China is a signatory to the treaty establishing the tribunal, it refuses to accept the court’s authority.
In recent years, satellite imagery has shown China’s increased efforts to reclaim land in the South China Sea by physically increasing the islands’ size or creating new ones altogether. In addition to piling sand onto existing reefs, China has constructed ports, military installations, and airstrips—particularly in the Paracel and Spratly Islands, where it has twenty and seven outposts, respectively. China has militarized Woody Island by deploying fighter jets, cruise missiles, and a radar system.
The United States, which maintains important interests in ensuring freedom of navigation and securing sea lines of communication (SLOCs), has expressed support for an agreement on a binding code of conduct and other confidence-building measures. China’s claims threaten SLOCs, which are important maritime passages that facilitate trade and the movement of naval forces. To protect its political, security, and economic interests in the region, the United States has challenged China’s assertive territorial claims and land reclamation efforts by conducting freedom of navigation operations and bolstering support for Southeast Asian partners. Washington’s defense treaty with Manila could draw the United States into a potential China-Philippines conflict over the substantial natural gas deposits or lucrative fishing grounds in disputed territory.
Also, in response to China’s assertive presence in the disputed territory, Japan has sold military ships and equipment to the Philippines and Vietnam to improve their maritime security capacity and to deter Chinese aggression.
Recent Developments
Upon assuming office in June 2022, Philippine President Ferdinand Marcos Jr. rejected the conciliatory stance toward China adopted by his predecessor, Rodrigo Duterte. The Philippines’ most contentious disputes with China center on the Second Thomas Shoal of the Spratly Islands, which lies within the Philippines’ 200-mile EEZ. In 1999, the Philippines intentionally grounded a ship to reinforce its territorial claims to the area which it calls the West Philippine Sea. Since then, the Philippine Coast Guard has conducted monthly resupply missions to its military contingent on the ship, known as the BRP Sierra Madre. Chinese Coast Guard vessels began to employ dangerous tactics to harass Philippine resupply missions in 2023, leading to heightened clashes. Collisions have become increasingly common, and the Chinese Coast Guard has used a military-grade laser and repeatedly fired water cannons against Philippine ships. On June 17, a Chinese vessel and a Philippine supply ship collided near the Second Thomas Shoal; both sides blamed the other for the incident.
Amid the rise in tensions with China, the Philippines has strengthened its partnerships with other Indo-Pacific neighbors. Marcos has signed deals to increase base access, joint exercise training, and weapons transfers with the United States. In March 2024, U.S. Secretary of Defense Lloyd Austin confirmed that the United States’ Mutual Defense Treaty with the Philippines extended to both countries’ armed forces, public vessels, and aircraft in the South China Sea. Meanwhile, Japan has also stepped up its presence in recent years by selling military equipment to the Philippines and Vietnam to improve maritime security capacity.
China Targets Philippine Patrol Plane
Chinese forces on the disputed Subi Reef fired three flares toward a Philippine surveillance aircraft during a routine patrol in the South China Sea, though the plane was unharmed and completed its mission (AP).
China Expands Intelligence Gathering in South China Sea
China has boosted its radar, antenna arrays, and electronic systems on at least three disputed reefs in the Spratly Islands to enhance surveillance and support naval and coast guard operations, according to a new report; the upgrades aim to strengthen Chinese military control over the region (Bloomberg).
Philippines and China Deploy Vessels Near Scarborough Shoal
The Filipino deployment followed the country’s coast guard encountering Chinese ships operating in contested waters; China responded with additional military patrols, and both sides issued radio challenges and reaffirmed competing sovereignty claims (Newsweek).
U.S.-China Maritime Security Talks
Military delegations from both countries met in Hawaii for several days of candid discussions on regional air and maritime risks as part of their revived Military Maritime Consultative Agreement dialogue; Beijing used the talks to object to U.S. naval transits in the South China Sea (Reuters).
Chinese Ships Disrupt Philippine Supply Route
Filipino officials suggested that Chinese Coast Guard vessels attempted to jam communications among Philippine forces during a supply run to the grounded BRP Sierra Madre ship at the contested Second Thomas Shoal, though Manila said the delivery was ultimately completed (AP).
Philippines Aims for Code of Conduct in South China Sea
Manila said it seeks to finalize a legally binding code during its ASEAN chairmanship next year, noting growing alignment between the bloc and China on concluding the long-delayed talks (Reuters).
China Commissions Third Aircraft Carrier
The Fujian, Beijing’s first domestically designed carrier equipped with electromagnetic catapults, marks a significant step in Chinese President Xi Jinping’s plan to build a “world-class” navy by mid-century; military analysts say the carrier enhances China’s ability to project power into the Pacific, though its conventional propulsion still limits range compared to U.S. nuclear-powered fleets (AP).
Canada, Philippines Sign Defense Pact at APEC
The Philippines and Canada signed a Status of Visiting Forces Agreement (SOVFA) allowing soldiers to train on each other’s soil, marking Manila’s fifth defense partnership to counter China’s assertive stance in the South China Sea (Reuters). Meanwhile, in Vietnam, U.S. Defense Secretary Pete Hegseth pushed for closer security ties with Hanoi as the two countries discuss potential U.S. arms sales, including C-130 transport aircraft and helicopters, as Vietnam attempts to diversify away from Russian weapons (AP).
China Monitors Philippine-Led Patrol
China’s military said it shadowed a Philippine joint patrol in contested waters and accused Manila of stirring regional tensions, as Australia, New Zealand, and the United States also conducted drills nearby; Beijing reiterated its sweeping maritime claims despite a 2016 international tribunal ruling rejecting them (Reuters).
Joint U.S.-Philippines Military Task Force
During talks on the sidelines of an ASEAN defense meeting, Washington and Manila unveiled a new combined task force aimed at boosting coordination around the contested South China Sea; in a separate meeting with Chinese officials, U.S. Defense Secretary Pete Hegseth also pressed Beijing over pressure on U.S. regional partners (Reuters). Newly inaugurated Japanese Prime Minister Sanae Takaichi likewise told Chinese President Xi Jinping of her country’s concerns surrounding China’s activity in the South China Sea (AFP). Finally, Hegseth also met with Malaysian officials to reiterate the U.S. commitment to Indo-Pacific security (AP).
China-Australia Thaw
Meeting on the sidelines of the ASEAN summit in Malaysia, Australian Prime Minister Anthony Albanese and Chinese Premier Li Qiang committed to maintaining stable bilateral ties amid continued military collisions in the South China Sea, including a Chinese jet’s recent encounter with an Australian patrol aircraft (Reuters).
Chinese Activity in Scarborough Shoal
Satellite imagery indicates China has deployed a new floating barrier blocking access to the lagoon at the contested Scarborough Shoal, escalating tensions with the Philippines amid repeated confrontations in recent weeks (SCMP).
Singapore’s New Warship
Singapore, a U.S. partner in the South China Sea, launched its largest and most complex warship to date; it can serve as a base for unmanned air, surface, and underwater missions (Newsweek). Singapore is building six such ships as the country aims to preserve access to sea routes for trade and military purposes (CNA).
Australia Condemns Chinese Military Behavior
Australia issued a formal diplomatic protest after a Chinese Su-35 jet released flares near an Australian P-8 patrol aircraft over the South China Sea, with Defense Minister Richard Marles labeling the incident “unsafe and unprofessional;” Beijing said the Australian flight violated its sovereignty (ABC).
China Expels Two Philippine Aircraft
Beijing claimed that the planes had “illegally entered” Chinese airspace over the Scarborough Shoal, as Manila accused China of endangering the pilots and called the move a violation of international law; the encounter marks the second confrontation between the countries over the past two days (SCMP). Meanwhile, a Russian naval force arrived at Vietnam’s port of Da Nang for a “friendly visit,” per the Russian Embassy, marking Moscow’s latest show of force in the disputed South China Sea; analysts say the move signals Russia’s intent to strengthen ties with Vietnam and align more closely with China (Newsweek).
China-Philippines Collision
A Chinese coast guard ship rammed and damaged the Philippine government vessel BRP Datu Pagbuaya, while firing powerful water cannons at two other Philippine vessels; the incident occurred just 1.6 nautical miles off Thitu, an island inhabited by Filipinos but claimed by China (AP). Beijing accused the Philippine ships of violating its sovereignty, while Manila vowed not to yield “a square inch” of territory (Reuters).
Philippines Expands U.S. Military Access
Manila approved a $975,000 U.S.-funded project to upgrade the Naval Detachment Oyster Bay in Palawan, enhancing support for small boats and unmanned vessels as Washington deepens its presence near contested areas of the South China Sea (SCMP).
Philippines Says China Increased Aggression at Sea After Deadly Collision
Philippine National Security Adviser Eduardo Año claimed at least two Chinese crew members died in the August 11 collision, saying the incident “brought shame” to China’s military; Manila vowed to maintain its presence at Scarborough Shoal despite Chinese attacks earlier this week (Bloomberg).
Chinese and Philippine Ships Collide Near Scarborough Shoal
Beijing accused a Philippine vessel of ramming its coast guard near the disputed Scarborough Shoal, while Manila said Chinese forces damaged its ship with water cannons, injuring a crew member; the confrontation occurred six days after China designated part of the Shoal as a nature reserve (AP). Meanwhile, the United Kingdom formally expressed interest in a Visiting Forces Agreement allowing mutual troop deployments with the Philippines (Reuters).