Geopolitical Developments Brief | North & Southeast Asia | Week #21

Weekly developments across key security and political flashpoints in North and Southeast Asia

Security developments this week were shaped by intensifying great power signalling and continued consolidation of strategic positions across key regional flashpoints. Taiwan featured prominently in US–China engagement following President Trump’s visit to China, raising concerns over strategic bargaining, while tensions in the South China Sea remained elevated amid ongoing infrastructure expansion and maritime friction. At the same time, North Korea further reinforced its military posture along the inter-Korean border, and instability persisted across mainland Southeast Asia, with renewed tensions along the Cambodia–Thailand border and continued conflict dynamics in Myanmar.

South China Sea Developments

Tensions in the South China Sea remained elevated this week with continued construction and presence-building across disputed features. The Philippines proceeded with infrastructure upgrades on Pag-asa Island (Chinese: Zhongye Dao) and Lawak Island (Chinese: Mahuan Dao), which Beijing criticised as “illegal activities” on Chinese-claimed territory. Manila rejected these claims, maintaining that such developments fall within its sovereign rights. Additionally, attention this week focused on China’s ongoing dredging and expansion at Antelope Reef in the Paracel Islands, located roughly 216 miles from Da Nang, in what analysts describe as China’s first major new artificial island project since 2017. As noted in last week’s update, Vietnam has also continued to reinforce its position across the Spratly Islands through ongoing expansion and infrastructure development.

Activity at sea remained closely linked to these developments. Chinese vessels operated near the Pag-asa cays, including a research ship whose personnel were reported to have landed on nearby sandbars, prompting a Philippine Coast Guard response. Chinese scientists were also reported to have landed on Sandy Cay reef, while coast guard and research vessels maintained a persistent presence in surrounding waters. Alongside these activities, China continued to expand its military posture. The aircraft carrier Liaoning and its strike group conducted live-fire and long-range exercises in the western Pacific, while Beijing is also developing what has been described as a “Great Wall of undersea sensors” to detect foreign submarines and strengthen control over maritime domains.

Across Southeast Asia, countries continued to strengthen their security positions through a combination of national measures and external partnerships. The Philippines further deepened defence cooperation with Japan, including expanded military engagement and ongoing discussions on defence equipment and maritime security collaboration. Indonesia also advanced its engagement with the United States through a Major Defense Cooperation Partnership, focused on training, capacity-building and operational coordination. At the same time, Jakarta emphasised its strategic autonomy, with officials stating that a letter of intent on potential US airspace access involved “no commitment”. These dynamics were further shaped by broader geopolitical developments, with the Trump–Xi summit and its emphasis on “constructive strategic stability” raising concerns in Indonesia that Southeast Asian interests, including maritime disputes, could become secondary to great power accommodation.

Japan’s role in the South China Sea continued to expand in a more assertive direction. During recent US–Philippines exercises, Japan deployed combat personnel and launched a Type 88 shore-based anti-ship missile, marking a notable extension of its operational involvement. It has also expanded defence engagement with regional actors, including discussions with the Philippines on the possible importation of Japanese defence equipment such as missiles, aircraft and radar systems. Chinese sources characterised these developments as “meddling” and indicative of broader geopolitical ambitions, arguing that Japan is seeking to expand its military presence and influence in the region.

Taiwan Strait Developments

Tensions in the Taiwan Strait came into focus this week during US President Donald Trump’s visit to China, where Taiwan figured prominently in his discussions with Chinese President Xi Jinping. According to reporting, Xi reiterated that Taiwan remains the most sensitive issue in US–China relations and warned that mishandling it could lead to confrontation, while Trump indicated that US arms sales to Taiwan could be reconsidered in the context of broader bilateral negotiations.

The visit raised concerns in Taipei over the possibility that Taiwan could become a bargaining chip in US–China relations. The exchange underscored how Taiwan continues to feature as a central issue in strategic bargaining between the two powers, with potential implications for existing security commitments. Taiwanese officials reiterated that China’s ongoing military activities remain the primary source of regional instability, while President Lai Ching-te stated that Taiwan would not provoke conflict but would also not give up its sovereignty in response to external pressure.

Political signalling shifted again later in the week as concerns in Taipei were partly eased after Trump indicated a willingness to speak directly with Taiwan’s President Lai Ching-te, breaking a decades-long diplomatic protocol, while also stating that a decision on future US arms sales to Taiwan would be made soon. While the prospect of direct engagement was welcomed in Taiwan, it drew strong opposition from China, underscoring the continued sensitivity of US–Taiwan interactions in the broader US–China relationship.

These developments also carried wider regional implications. Philippine President Ferdinand Marcos Jr stated that the Philippines would likely be drawn into any conflict over Taiwan, citing both geographic proximity and the presence of more than 200,000 Filipino nationals on the island, while emphasising that Manila does not seek involvement and continues to adhere to a “one-China policy”.

Korean Peninsula Developments

Tensions on the Korean Peninsula remained high this week, as North Korea intensified its military posture along the inter-Korean border. Building on last week’s constitutional shift formally recognising the two Koreas as separate states and previously reinforcing the regime’s nuclear deterrence posture, leader Kim Jong Un ordered frontline units to be strengthened and called for transforming the southern border into an “impregnable fortress”, while emphasising combat readiness and the need to adapt to evolving forms of warfare. These directives were reinforced through meetings with senior military commanders and reflected a broader effort to modernise forces and deter perceived threats from what Pyongyang continues to describe as its “arch enemy”.

Weapons development also remained a key focus. Satellite imagery indicated that North Korea conducted a rocket engine test at the Sohae space launch complex, likely linked to efforts to revive its military reconnaissance satellite programme. The test forms part of a broader push to enhance missile and surveillance capabilities, including both liquid- and solid-fuel systems.

Diplomatic dynamics showed increasing fragmentation. Following President Trump’s visit to China, the United States and China reiterated a shared goal of denuclearising North Korea, but this was contrasted by a joint statement from China and Russia opposing sanctions and external pressure on Pyongyang, arguing such measures undermine regional stability. At the same time, North Korea expanded its diplomatic outreach, agreeing with Vietnam to strengthen cooperation through foreign ministerial talks and party-level exchanges.

Inter-Korean relations remained strained but showed limited, symbolic openings. A North Korean women’s football team travelled to South Korea for the first time in eight years, marking a rare cross-border exchange despite ongoing political tensions. At the same time, debate intensified in Seoul over a proposed “two-state” framework for managing relations with the North, with the government suggesting a shift toward recognising both sides as sovereign entities while maintaining a long-term goal of reunification and further clarified in parliamentary discussions emphasising a “peace-oriented two-state approach” distinct from Pyongyang’s hostile framing.

Myanmar Developments

Tensions in Myanmar remained high this week, with the military reporting further gains in the ongoing civil war. Authorities said they had recaptured the Thai border town of Mawtaung after a two-week offensive involving more than 200 clashes, and regained control of additional towns near both the Thai and Indian borders, including Tonzang. The fighting points to continued efforts by the military to regain control over key border crossings and trade routes.

At the same time, humanitarian conditions on the ground continue to worsen. Rising food and fuel prices have pushed up the cost of basic goods across the country, with the sharpest increases in conflict-affected areas. Around one in four people, about 12.4 million, are now considered acutely food insecure, while 3.7 million remain displaced by ongoing fighting.

Diplomatic signals were mixed. Malaysia’s foreign minister said Myanmar appears more open to talks with opposition groups following recent meetings with representatives of the military-backed government. At the same time, ASEAN remains divided on how to deal with Naypyitaw, with some members pushing for re-engagement despite limited progress with ASEAN’s peace proposal. Despite this, practical cooperation continues in specific areas, including an agreement between Thailand and Myanmar to coordinate on transboundary haze pollution through shared data and monitoring systems.

Cambodia–Thailand Developments

Tensions along the Cambodia–Thailand border continued this week, with Thailand upgrading its military capabilities, including naval and air power, while both sides reinforced positions around disputed farmland in Banteay Meanchey province. Cambodia organised a joint visit with ASEAN observers to Seila Khmer Village, including farmland between Border Markers 48 and 49, following reports that Thai military personnel had prevented Cambodian farmers from accessing the land. Cambodian authorities maintained that the area remains under their administration, while the mission was intended to assess the situation on the ground and monitor compliance with the ceasefire agreed in late 2025. A Thai public opinion poll meanwhile showed support for avoiding renewed conflict with Cambodia, while still backing increased defence spending.

Disagreement also extended to the legal framework governing the border. A Thai Senate committee called for the revocation of the MoU 2000 (MOU43), which underpins land boundary demarcation through the Joint Boundary Commission, arguing that it is based on contested French-era maps. The move follows Thailand’s earlier decision to abandon a separate agreement on maritime claims and joint energy exploration (MoU 44). Cambodian officials rejected any unilateral changes, insisting that all boundary issues must remain within the JBC process, while calling for the resumption of formal demarcation talks. Thailand, in turn, moved to restructure its JBC negotiating team.