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Emerging Security-Related Equations in Southeast Asia

Dr Temjenmeren Ao is Associate Fellow in the Southeast Asia & Oceania Centre at Manohar Parrikar Institute for Defence Studies and Analyses.
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  • April 19, 2024


    Beijing’s attempt to unilaterally change the regional status quo by force and increasing instances of its grey zone activities in Southeast Asia’s disputed waters along with the worrying trend in the Taiwan straits are key factors that are bringing the United States, Japan and Philippines together. As the great power competition between US and China takes on a global dimension, increasing tensions in the South and East China Sea and the Taiwan Straits has altered the regional security-related equations.

    The first-ever US–Japan–Philippines trilateral summit held in Washington DC on 11 April 2024 signals a new chapter in the emerging security-related equations in the Indo-Pacific. The three countries’ coming together is driven by a common perceived threat. In recent years, their respective bilateral alliances have seen a revival on account of new developments in the South and East China Sea and the Taiwan Straits.

    Japan and Philippines both have separate territorial disputes with China, in the former’s case, the Senkaku Islands in the East China Sea and in the latter’s areas of the South China Sea. Tensions between the Philippines and China in recent years have been running high with numerous incidents taking place in the South China Sea. Japan continues to face pressures from Chinese coast guard ships that regularly sail near its islands close to Taiwan in the East China Sea.  

    Further, recognising the worrying trends in the Taiwan Straits, the US along with Japan, and the Philippines, are working to deepen and better network their alliances. The US has made clear that it will help Taiwan defend itself from Chinese aggression, as required by the Taiwan Relations Act, and is likely to directly intervene in the case of an overt attack across the strait. The northernmost of the main Philippine islands, Luzon, is just around 200 miles from the southern coast of Taiwan. In a Taiwan contingency, the Philippines’ strategic location could greatly assist the United States’ ability to respond to a crisis.1    

    The trilateral Summit is expected to enhance joint military efforts as well as economic and infrastructure partnerships. This includes the launching of the Luzon Economic Corridor, which will support connectivity between Subic Bay, Clark, Manila and Batangas in the Philippines. The Leaders Joint Vision Statement expressed serious concerns over China’s aggressive behaviour and actions in the South China Sea and reiterated strong opposition to Beijing’s attempt to unilaterally change the status quo by force in the East China Sea.2 Increasing instances of China’s grey zone activities in these disputed waters along with the worrying trend in the Taiwan straits are key factors in bringing the three countries on a common platform. This common threat perception is one of the many factors which is leading to the emergence of new alliances and partnerships, shaping Southeast Asia’s security equations.   

    Renewed Alliances and New Partnerships

    With the end of the Cold War, Southeast Asia was faced with a new strategic environment marked by new security challenges. Under the new circumstances, ASEAN began establishing new regional mechanisms to improve institutional capacity in order to respond to emerging security challenges, some of which are transnational in nature. Further, Southeast Asia also witnessed political transition amongst some of the ASEAN countries. These transitions re-defined the political landscape in the region, making it more open and democratic which also got filtered into shaping the emerging ASEAN-led security mechanisms.3

    The security environment in Southeast Asia since the 1990s has changed significantly. External powers that were only marginally involved in Southeast Asia at the turn of the 21st century began to intensify their presence in the region. Apart from the new multilateral mechanisms led by ASEAN, new security arrangements comprising of old defence alliance are being forged by the US. These defence alliances were established during the Cold War between the US and some of the Southeast Asian countries to manage the containment of the Soviet Union. Amidst the US–China strategic competition which in recent years has taken on a global dimension, new security challenges have led to the increasing presence of other powers in the region.

    US Reviving Old Defence Alliances

    In an effort to support a peaceful and stable, rules-based Indo-Pacific with Southeast Asia at the centre, the US is building its military presence in the region by reinforcing its old defence alliances. Further, through its Indo-Pacific strategy, the US is boosting the profile of initiatives such as the Quad, establishing new security arrangement such as the AUKUS (Australia, UK and US) and trilaterals with Japan–Philippines and Japan–Republic of Korea. The relations that each of the Southeast Asian countries has with the US is based on their historical ties, economic, security dependencies, and values-based compatibilities.

    The US-led bilateral defence alliances in Southeast Asia continues to predominantly shape the region’s evolving security partnerships and arrangements. The US-centric security systems in the region built during the Cold War are beginning to see a re-orientation amidst enhanced rivalry with China. During the Obama administration, the US began to rebuild its relations with Southeast Asia by deepening its engagement with ASEAN. The US joined the Treaty of Amity and Cooperation (TAC) in 2009 and President Obama regularly visited Southeast Asia to participate at the East Asia Summit.

    President Donald Trump, withdrawing from the Trans-Pacific Partnership (TPP) shortly after taking office and not attending any of the EAS meetings, gave the impression that the region was not a top priority for the US. Under President Biden however, there is a renewed attempt to build engagement with the region. There have been a number of high-level visits by senior US officials to the region, including by Biden to the ASEAN–US Summit held in Cambodia in November 2022, during which the relationship between the two sides was elevated to a Comprehensive Strategic Partnership (CSP).

    The Indo-Pacific Strategy of the United States released in February 2022 underlined the importance of ASEAN and its centrality and paved the way for the early conclusion of the CSP. The document also flagged the ways in which the US will seek to further deepen its traditional partnership with Southeast Asian countries. This included embarking on new areas of cooperation such as health, climate change and environment, energy, transportation, and gender equality through exploring possible cooperation between Quad and ASEAN.4

    China’s Increasing Strategic Presence 

    From the later half of the 1990s, the influence of rising China began to permeate Southeast Asia. Since the late 1990s, China has played a leading role in the establishment of a number of high-profile regional institutions, including the Shanghai Cooperation Organisation (SCO), the Boao Forum for Asia, and so on. China keeps an eye on the proactive US policy towards Southeast Asia whereby it perceives mechanisms such as the Quad and AUKUS as Washington’s measures to contain Beijing. China continues to solidify its engagement with Southeast Asia by participating in ASEAN’s multilateralism with Beijing enhancing its relations to the level of a Comprehensive Strategic Partnership in November 2021.

    However, it is important to note that China focuses primarily on its bilateral relations with countries in Southeast Asia by leveraging economic relations to strengthen ties.5 In the post-pandemic period, China has further intensified its focus on Southeast Asia, to renew and build, by regularly attending ASEAN multilateral meetings and high-profile visits to Southeast Asian countries by President Xi Jinping and other senior government officials.

    China’s intensified diplomatic efforts within the region, both through ASEAN and bilaterally, have yielded significant dividends. As per the State of Southeast Asia 2024 survey, there has been a notable surge in China’s influence across Southeast Asia, with a growing number of regional respondents recognising its expanding role in the region. This year marked the first time that China with 50.5 per cent has emerged as the preferred alignment choice over the US, as compared to 38.9 per cent in 2023. Apart from the Philippines, Singapore and Vietnam, all countries in Southeast Asia have shown a leaning towards China, particularly those that have benefitted from China’s Belt and Road Initiative (BRI), such as Malaysia, Indonesia, Laos, Brunei and Thailand.6  

    Other Security Alignments in Southeast Asia

    The exposure to and engagement with China has also left Southeast Asia stuck in the middle of an extremely uncomfortable position. Further, some of the Southeast Asian countries are also struggling to ward off China’s increasingly assertive maritime behaviour since the turn of the century. ASEAN’s incapability to stand up against the ongoing coercive action in the disputed South China Sea is also reshaping the region’s security architecture. As the nature of threats have transformed over time, there has also been an emerging divergence about threat perceptions amongst the ASEAN countries. This continues to weaken the ASEAN-led mechanisms towards collectively addressing the security challenges. In this emerging scenario, the ASEAN-centred regional security architecture is under considerable challenge and is enabling the formation of mini-laterals.

    Enhancement of the ‘Five Power Defence Arrangements’

    The region’s oldest military partnership, the Five Power Defence Arrangements established in 1971 comprising of Australia, Malaysia, New Zealand, Singapore, and the United Kingdom, is seeking to forge greater strategic and defence cooperation. In the 21st century, the FPDA began to enhance cooperation towards dealing with emerging asymmetric threats. These included terrorism, piracy, protection of Exclusive Economic Zones (EEZ), disaster relief, and smuggling of illicit drugs. Reflecting on the changing nature of security in the region, the FPDA today is increasingly focused on exercises related to non-conventional threats in the maritime domain.

    Over the past two decades, although the FPDA is explicitly defensive in nature, the increase in illegal and aggressive Chinese action in the South China Sea has drawn attention of its members. The FPDA has gradually expanded its focus from the conventional defence of peninsular Malaysian and Singaporean air space, to large-scale combined and joint military exercises designed to meet emerging conventional and non-conventional security threats extending into the South China Sea. The exercises relate to building capacities to address threats to maritime security, including defence of Sea Lines of Communications (SLOCs), surveillance of merchant shipping, and counterterrorism.7       

    Revival of the ‘Quad’

    As the US–China competition intensifies, the Quad in recent years has gained considerable prominence. The four Quad countries share fundamental values, such as the rule of law and human rights, and is a coalition which seeks to strengthen a free and open international order. The idea of Quad took root at the end of 2004 when an earthquake off the coast of Sumatra, Indonesia and the tsunami hit the Indian Ocean.8 This natural calamity resulted in a brief coordination among the naval forces of the US, India, Japan and Australia.

    The idea was later developed into a formal proposal by the Japanese PM Shinzo Abe in 2006. This was formally endorsed by Prime Minister Manmohan Singh during his visit to Tokyo in December 2006. In May 2007, at the margins of the ARF, there was a formal meeting of the senior officials of the Quad nations. In September of the same year, India also hosted a massive multilateral naval exercise involving the US, India, Japan, Australia and Singapore in the Bay of Bengal.

    However, there was reservation amongst the four Quad nations as the idea of the four democratic countries coming together was seen by other nations as an attempt to contain China. Following the fall of the Abe government in Japan and that of the John Howard government in Australia in 2007, the initiative ran out of steam. While Abe’s successor Fukuda was lukewarm, the Kevin Rudd government in Australia explicitly suggested that it is not interested in the Quad.9

    In November 2017, senior officials from the Quad nations met in Manila for the first time in nearly a decade, and the first-ever Quad foreign ministers’ meeting was held in September 2019.  During the virtual Quad Leaders’ Summit held in March 2021, the four countries agreed to advance practical cooperation on quality infrastructure and non-traditional security issues. At the same time, the Leaders agreed to establish working groups on COVID-19 vaccines, climate change, and critical and emerging technologies, redefining the Quad framework from a security-centred to a more comprehensive cooperation paradigm. Additionally, the Leaders affirmed strong support for the ASEAN Outlook on the Indo-Pacific (AOIP) as well as for ASEAN centrality.10  

    The most defining aspect of the revived Quad relate to the diverse areas of cooperation. In addition to shaping a rules-based international order for the realisation of a ‘Free and Open Indo-Pacific’ and strengthening the Malabar exercise and other maritime security cooperation, the Quad is now undertaking initiatives in new areas such as climate change, resilient supply chains and disaster response.11 The revival of the Quad in the aftermath of the COVID-19 pandemic has been favourably viewed by Southeast Asian countries. This qualitative shift of the Quad with due consideration for ASEAN and building cooperation that keeps the interest of the region in mind is also altering the perception about the grouping.

    New Security Alliance ‘AUKUS’

    On 15 September 2021, a new enhanced trilateral security partnership, AUKUS, was announced. This cooperation framework is centred on the provision of nuclear-powered submarine technology from the US and the UK to Australia.  According to the joint statement, the emerging complexities in the Indo-Pacific which would have wide implications for all across the region, necessitated the need for this ‘next-generation partnership’ that seeks to deliver security and stability. The statement clearly outlined AUKUS’ intent to enhance the “growing network of partnership in the Indo-Pacific region” including with the ASEAN.12

    The formation of the new security alignment has received a mixed response from the Southeast Asian countries.  Malaysia and Indonesia have shared their concerns with Jakarta stating that the trilateral security arrangement could trigger an arms race in the region.13 They feared that AUKUS would undermine ASEAN’s goal to keep Southeast Asia a nuclear weapon-free zone and further heighten military tensions between the US and China. Other ASEAN countries including Vietnam noted that the new trilateral security arrangement should strive for the “...same goal of peace, stability, cooperation and development in the region and the world over...”.14 Vietnam and the Philippines, which are in a dispute with China over the South China Sea, along with Singapore, that seek greater US military engagement, have a more accepting view of the AUKUS.15  

    At the 31st Australia–United States Ministerial Consultations (AUSMIN) held on 16 September 2021 at Washington D.C., both sides reaffirmed their commitment to Southeast Asia, ASEAN centrality and ASEAN-led architecture such as the East Asia Summit, which they recognised “ the region’s premier, leaders-led forum for addressing strategic challenges and expressed their ongoing support for the practical implementation of the ASEAN Outlook on the Indo-Pacific...”.16 The establishment of AUKUS adds yet another dimension to the region’s security environment. The increasing number of multilateral security arrangements in the region which includes external actors though makes the ASEAN countries concerned about possible negative regional fallouts.


    As the great power competition between US and China takes on a global dimension, increasing tensions in the South and East China Sea and the Taiwan Straits has altered the security-related equations. While the traditional defence alliances are getting revived in view of the new developments, there is also increasing participation of other regional powers with Southeast Asian countries. These new alignments are either bilateral or through various platforms including the ASEAN-led security processes. This increasing participation has meant that unlike in the past, where the US had sole monopoly in terms of establishing security arrangements, today it is becoming an increasingly crowded space with multiple players. Therefore, the security equations in Southeast Asia will be shaped by the nature of alliances and partnerships being forged.

    Views expressed are of the author and do not necessarily reflect the views of the Manohar Parrikar IDSA or of the Government of India.