
Indonesia’s underwater domain awareness (UDA) is a critical gap that the Quad security partners—Australia, India, Japan and the United States—can and should fill. UDA includes detecting and monitoring underwater activities, including tracking submarines and protecting underwater resources against espionage.
It’s also a means for researching marine environments, which is vital for economic and environmental advances. Collective support from the Quad nations can be instrumental in bridging Indonesian technological and operational gaps to secure its underwater domain.
The underwater realm has become a contested area in the Indo-Pacific, placing significant pressure on the Indonesian military and law enforcement to build the country’s UDA.
First, the South China Sea dispute and the rivalry between the US and China raise concerns for regional littorals. In 2020, Indonesian fishermen discovered a Chinese uncrewed submarine near South Sulawesi. Indonesian authorities also suspect that Chinese oceanographic vessels using the Sunda and Lombok straits are gathering data that could aid China’s submarine operations.
Second, the geopolitical rivalry is also leading to the proliferation of submarines in the region. All Southeast Asian nations, except landlocked Laos, have acquired submarine fleets or intend to do so. The AUKUS trilateral partnership of Australia, the UK and the US seeks to strengthen Australia’s submarine capabilities by developing nuclear submarines to be operated by Australia. The submarines could be positioned near Indonesian waters, raising safety concerns, as Indonesia also operates submarines. The sinking of the Indonesian submarines KRI Nanggala during a torpedo drill in April 2021 was a reminder of the danger of underwater operations.
Third, Indonesian waters are vast, and monitoring the seabed is vital, including to protect subsea pipelines and cables.
These issues have prompted Indonesia to prioritise the development of UDA.
However, the ambition is inconsistent with Indonesia’s limited capacity in undersea warfare. The Indonesian navy currently operates four diesel-electric attack submarines of the Cakra and Nagapasa classes. Additionally, it has bought 11 Airbus AS 565MBe Panther helicopters for antisubmarine warfare. These have short range and endurance compared with maritime-patrol aeroplanes.
In March 2024, Indonesia finalised an agreement with the French company Naval Group and Indonesia’s own PT PAL to build two Scorpene class submarines with lithium-ion batteries at PT PAL’s shipyard. Indonesian defence experts note that the Scorpenes will be able to deploy uncrewed submarines.
According to Indonesia’s navy chief, Admiral Muhammad Ali, the country needs at least 12 full-size submarines to monitor its maritime territory adequately. Additionally, some Indonesian scholars note that the navy has proposed establishing underwater detection networks similar to the US Sound Surveillance System, better known as SOSUS, at the nation’s strategic chokepoints. This would be a major step forward for UDA, but details of are murky.
Indonesia’s UDA capabilities will not only serve a military purpose; they will support the country’s economic and environmental security. They can provide Indonesia with a significant advantage in exploring seabed resources, enabling Jakarta to uncover and use valuable marine resources effectively. UDA can also improve tsunami early warning systems through deep-water acoustic sensors, similar to systems used in India.
However, Indonesia is encountering constraints in developing UDA. They include inadequate infrastructure, shortage of money, limited personnel training and insufficient access to advanced sonar systems, underwater drones and satellite surveillance. Integrating data from multiple sources for real-time analysis remains a major hurdle. Addressing those gaps requires international collaboration, particularly with technologically advanced and strategically aligned partners such as the Quad nations.
They can support Indonesia in developing UDA by providing technological and operational assistance.
The Quad has the capacity to provide Indonesia with advanced surveillance technology, which includes underwater drones, sonar systems and satellite imaging tools. The Quad’s Maritime Initiative for Training in the Indo-Pacific can equip Indonesian personnel with the essential skills to operate and maintain those technologies. Joint maritime exercises would enhance Indonesia’s tactical and operational strengths. Moreover, the Quad can help Indonesia establish infrastructure for efficient data integration and real-time analysis, leveraging India’s expertise from its Information Fusion Centre for regional maritime security.
Second, the Quad can help to secure Indonesia’s maritime infrastructure. Japan has decades of experience in operating underwater sensor systems for monitoring waters around its islands and especially ports. It could help upgrade Indonesia’s port security and improve its monitoring of underwater traffic and infrastructure. The Quad’s Australia-based Cable Connectivity and Resilience Centre can build Indonesia’s capacity in that area.
Indonesia’s quest for enhanced UDA is both a national priority and a regional necessity. In 2023, Indonesia’s then-president Joko Widodo wished to view the Quad and AUKUS as ‘partners, not competitors’. According to a survey conducted by Indonesia’s National Research and Innovation Agency in December 2023, 51 percent of Indonesian government officials agreed that the Quad ‘strengthens regional security and stability’. Among academics, more than 60 percent agreed. The Quad’s concrete security assistance to Indonesia, such as in UDA capabilities, might increase this proportion further.