The seas of the ASEAN region are a geostrategic domain where geopolitics and digital security intersect. Maritime cybersecurity threats and disruptions to critical underwater infrastructure could arise due to major powers competing to establish spheres of influence and if regional tensions escalate.
Maritime Digitalisation and Riskier Geostrategic Domain
The region is not new to such issues. ASEAN countries have embarked on digitalisation for national socio-economic development and regional digital integration. Since the first Trump administration, they have also navigated the technological Cold War between China and the US, particularly in 5G networks, Internet-of-Things (IoT) devices, and semiconductors.
For example, Thailand signed a memorandum of understanding (MOU) with Huawei in 2022 to develop smart ports despite the US pressing its allies to proscribe Huawei from providing digital solutions. To Thailand, the adoption of 5G technologies was a careful balance of foreign relations, national interests, competitive pricing, and different cyber threat perceptions.
Another example is the region adopting the inaugural ASEAN Maritime Outlook (AMO) in 2023 under Indonesia’s ASEAN chairmanship. The Outlook highlights ASEAN guidelines for port digitalisation and the need to enhance preparedness against cyber-attacks due to the growing digitalisation of the maritime transport industry. It complemented calls by former Indonesian foreign minister Retno Marsudi for ASEAN countries to strengthen maritime cooperation to prevent the region from becoming an “epicentrum of conflict.”
However, the region should now expect more turbulence in this geostrategic domain. At the opening of the Singapore Maritime Week 2025, Singapore’s Senior Minister Lee Hsien Loong spoke about the worsening geopolitical uncertainties and cautioned that the “world has not seen a similar situation since World War II”.
Given this backdrop, the region should note that maritime cybersecurity and critical underwater infrastructure could be subjected to heightened coercive influence activities or even hybrid warfare if a maritime conflict happens in or near the region.
Maritime Cybersecurity
Maritime cybersecurity threats would be most disruptive to supply chains and regional peace if they affect maritime chokepoints’ riskier and narrower sections, such as the Straits of Malacca and Singapore, Sunda Strait and Lombok Strait. Two plausible threat scenarios come to mind.
First, state-backed threat actors could seize control of a vessel by spoofing AIS (Automatic Identification System) and GNSS (Global Navigation Satellite System) or deploying malware in a vessel’s internet-connected OT (Operational Technology) system. Threat actors targeting shipping companies transporting perishable or dangerous goods could disrupt shipping lines by holding the vessels hostage, akin to ransomware. Worse, they could weaponise the vessel to cause a blockade or grounding or collision and as an incendiary tool against other vessels or entrances to oil refineries.
Second, Southeast Asia is a maritime trade hub. Cyber-attacks on the digital systems of ports in the region could disrupt supply chains and inflict significant economic pain on Southeast Asian countries, which are major exporters to the global market.
Together, cyber-attacks targeting maritime systems on shore and at sea could serve the geopolitical objectives of influencing a target country’s foreign and defence policies. ASEAN countries should test their incident response plans to ensure strategic autonomy, as exemplified by the port-focused cybersecurity tabletop exercise conducted by Indonesia and the US in Surabaya last year.
Critical Underwater Infrastructure
Critical underwater infrastructure, especially submarine data cables, has been on the radar of ASEAN countries in recent years due to growing demand for data connectivity, geopolitical factors, cyber threats and sabotage incidents affecting the Baltic Sea and Taiwan Strait.
For example, Vietnam, which maintains a delicate balancing act between China and the US, is planning to build as many as ten submarine cables by 2030. As the US looks to Vietnam as a strategic partner to counter China, it has lobbied Vietnam to avoid engaging Chinese firms such as HMN Technologies due to cybersecurity concerns such as espionage and internet blockade during a military crisis. The US also shared intelligence with Vietnam on possible sabotage of existing submarine cables.
Another example is the Apricot submarine cable, which will come online in 2026 and has landing stations in six locations, including the Philippines and Indonesia. The Philippines and Indonesia are attractive options for the US and its allies to diversify cable routes to avoid connecting to Hong Kong and to circle the South China Sea, where Chinese forces are dominant.
However, the Apricot cable bypassed Malaysia due to the federal government’s cabotage policy in 2021 that allowed only domestic vessels to operate between the Peninsula and East Malaysia. Incidentally, this cabotage policy revived demands in East Malaysia for more autonomy from the federal government and sovereignty claims by descendants of the colonial-era Sulu Sultanate that used to rule over Sabah.
Analysis by a former NATO analyst noted the suspected closeness of the Sulu descendants’ lawyers to US tech giants that provided backing for the Apricot cable. It had also raised questions about whether the Sulu sovereignty claims intertwine with geopolitical competition in the South China Sea and whether US tech giants had an interest in challenging the federal government’s control over Sabah.
Choppier Waters Ahead
Choppier waters are afoot even as Southeast Asian countries continue to build cable connections with China for commercial reasons. Furthermore, the ASEAN Digital Ministers’ Meeting (ADGMIN) in 2024 highlighted the importance of a diverse submarine cable network for digital resilience. But will business continue as usual? This could depend on whether serious maritime cybersecurity incidents happen and influence threat perceptions and whether shifting China-US tensions impact their national interests.
On the one hand, China believes the US is exploiting submarine data cables for a “subsea Cold War” as part of a wider containment strategy. Relatedly, China’s actions in the South China Sea could enable a Chinese monopoly of submarine cables there. This could ensure strategic advantage over the region during times of conflict. China’s intent to project sea power could be one reason for its recent unveiling of a deep-sea cable-cutting tool that complements its fleet of autonomous submersibles.
To ameliorate international concerns over the intent of its growing sea power, China in March 2025 released a 44-page paper that positions itself as a responsible stakeholder in the area of submarine cables. A key point in the paper that the Chinese media highlighted is that submarine cables constitute the “foundation for jointly building a community with a shared future in cyberspace.”
On the other hand, the US and its allies would not be persuaded by China’s paper on the construction and protection of submarine cables. Instead, US military planners would more likely continue wargaming a future conflict with China over the Taiwan Strait or South China Sea. Based on a RAND Corporation report, one conflict scenario involves the Chinese controlling the global digital infrastructure to enable political and economic warfare. The US might conduct a cyber operation on targets in China and special operations to disable selected submarine cable landing stations in Asia, but this would result in a Chinese response.
As the geostrategic domain becomes increasingly risky, some Southeast Asian countries are advocating for more policy thinking about digital maritime security even as they push ahead with global trade, digitalisation and the ASEAN power grid, which includes overland and submarine cables.
For example, Singapore joined several countries in September 2024 to endorse a “Joint Statement on the Security and Resilience of Undersea Cables in a Globally Digitalised World” at the UN General Assembly. During the ASEAN Defence Ministers’ Meeting (ADMM) Retreat in February 2025, Singapore and Thailand jointly submitted a paper proposing that ASEAN militaries explore cooperation in the security of critical underwater infrastructure.
A concrete next step is for the ASEAN region to collaborate with international partners to translate policy thinking into practical mechanisms, which the ASEAN Secretary-General alluded to during the ASEAN Outlook on the Indo-Pacific (AOIP) Seminar Series on Submarine Cables in February 2025. At the strategic level, this step should dovetail with developing regional efforts to address cybersecurity threats in the maritime domain.
