Japan and the Philippines Bolster Defense Ties Amid South China Sea Tensions
Chinese vessels fire water cannons towards a Philippine resupply vessel.(Photo: Adrian Portugal/Reuters)
On Feb. 24, Japan and the Philippines agreed to establish high-level defense cooperation to expand equipment and technology sharing. The framework, finalized in talks between Japanese security adviser Gen Nakatani and Philippines Defense Secretary Gilberto Teodoro, will facilitate regular meetings between senior officials to assess the Philippines' defense needs. Japanese defense officials and industry representatives are also expected to visit the Philippines soon.
The deal comes amid rising tensions in the South China Sea, where the Philippines has increasingly confronted China over territorial disputes. Since 2023, Manila has filed numerous accusations against Chinese vessels of unsafe maneuvers, aggressive blockade tactics, and the use of coercive measures to assert control over contested waters. The disputed area has become a flashpoint for regional conflict, with incidents including the Chinese vessels’ use of military-grade laser pointers to temporarily blind Philippine sailors. These encounters have escalated near key Philippine-controlled outposts, such as Second Thomas Shoal, where the Philippines maintains a military presence aboard the beached warship BRP Sierra Madre as a symbolic marker of sovereignty.
The South China Sea dispute traces its origins to imperial expansion and post-war territorial ambiguity. In the 1930s, Japan expanded its empire into East and Southeast Asia, asserting control over key islands in the region, including the Paracel and Spratly Islands. After Japan’s defeat in WWII, these territories were left without clear ownership, leading to conflicting claims by multiple nations.
In 1947, the Republic of China published a map featuring an 11-dash line, asserting broad sovereignty over the South China Sea citing its historic right to the area dating from the Western Han Dynasty since 200 BCE. The claim was later inherited and modified by the People’s Republic of China into what is now the nine-dash line. The discovery of oil and natural gas reserves in the 1970s heightened competition for control, as Vietnam, the Philippines, Malaysia and Brunei stacked overlapping claims to the region.
China’s nine-dash line territorial claim (Photo: The Guardian)
In 2013, the Philippines challenged China’s maritime claims through arbitration under the United Nations Convention on the Law of the Sea (UNCLOS). The 2016 ruling by the Permanent Court of Arbitration in The Hague, Netherlands, declared that China’s nine-dash line had no legal basis, affirming Manila’s rights over disputed areas. China rejected the verdict outright, and continued its military buildup and maritime activities in defiance of the ruling.
In response to the PRC’s increasingly assertive claims over the South China Sea, Japan and the Philippines—once an imperial aggressor and their former victim—have strengthened their security ties. In December 2024, the Philippine Senate ratified Reciprocal Access Agreement (RAA), a landmark defense pact allowing for the deployment of Japanese forces in the country for joint military exercises, training, and humanitarian operations. Japan has steadily expanded its regional security role since former Prime Minister Shinzo Abe introduced the Free and Open Indo-Pacific (FOIP) strategy in 2016, promoting the rule of law, freedom of navigation, and regional stability. Among the states within the Association of Southeast Asian Nations (ASEAN), the Philippines has been the largest recipient of Japanese defense equipment and technology. Tokyo has provided 12 patrol vessels and 13 small high-speed boats and in May 2024, Japan agreed to a ¥64.3 billion loan for the acquisition of five additional patrol vessels.
The framework also reflects Japan’s broader security realignment, which includes the largest defense budget increase in its post-war history and a fundamental shift in its National Security Strategy (NSS). In 2022, Japan announced plans to double its defense spending to 2% of GDP by 2027, aligning its military commitments with NATO standards. The revised NSS also emphasized the importance of counter-strike capabilities, a significant departure from Japan’s previous self-defense-only stance, ingrained in its pacifist constitution.