Malaysia and Singapore Seal Historic Submarine Rescue Pact Amid Rising South China Sea Tensions

(DEFENCE SECURITY ASIA) — In a development underscoring the urgency of undersea security in Southeast Asia, the Royal Malaysian Navy (RMN) and Republic of Singapore Navy (RSN) have signed a landmark arrangement on Mutual Submarine Rescue Support and Cooperation.

The pact is designed to ensure both nations can immediately extend technical, operational, and logistical assistance if any submarine suffers distress, accident, or a potentially catastrophic incident beneath the waves.

The agreement was formally sealed by Admiral Tan Sri (Dr.) Zulhelmy Ithnain, Chief of the Royal Malaysian Navy, and Rear Admiral Sean Wat Jianwen, Chief of the Republic of Singapore Navy.

The signing was witnessed by Malaysian Defence Minister Datuk Seri Mohamed Khaled Nordin and Singapore’s Defence Minister Chan Chun Sing during the latter’s working visit to Malaysia, symbolizing the political weight behind the deal.

“This arrangement enables both nations to render mutual technical, operational, and logistical assistance should either side’s submarine encounter distress, accident, or any unforeseen incident,” said Mohamed Khaled.

“It also strengthens the interoperability between the Royal Malaysian Navy (TLDM) and the Republic of Singapore Navy (RSN) through the exchange of best practices as well as expanded opportunities for joint training and exercises.”

“Based on the ASEAN spirit and with Singapore being a neighbouring country, it is appropriate for us to have such cooperation,” he added.

The RMN emphasized that its Submarine Force Command and the RSN would serve as the principal agencies responsible for implementation, with National Rescue Coordinators from both countries appointed to guarantee seamless communication and execution.

The operational coverage zones extend across some of the world’s most critical maritime arteries, including the South China Sea, the Singapore Strait, and the Malacca Strait, ensuring rescue readiness across routes vital to both regional stability and global trade.

“This will ensure that rescue capabilities can be implemented in important maritime routes for regional security and international trade,” the RMN said in its official statement.

Both sides also confirmed their commitment to providing submarine rescue assistance under a full Submarine Escape and Rescue (SMER) framework, ensuring access to advanced rescue technology, standardized procedures, and up-to-date operational doctrine.

The cooperation encompasses the exchange of technical data, operational intelligence, and harmonization of rescue procedures to reduce reaction times in high-risk submarine emergencies.

Singapore’s Ministry of Defence described the framework as “a testament to the strong ties between both ministries and navies,” reinforcing the bilateral relationship as a cornerstone of ASEAN maritime security.

Malaysia’s Submarine Force: Strategic But Limited

Malaysia’s decision to establish a submarine force in the early 2000s was a watershed moment in its maritime strategy, reflecting the growing urgency of safeguarding sovereignty amid intensifying territorial disputes in the South China Sea.

The move was not merely about acquiring new military hardware but about projecting deterrence, extending operational reach, and signaling to both regional neighbors and extra-regional powers that Kuala Lumpur intended to defend its maritime claims with credible undersea capability.

Although the Royal Malaysian Navy’s (RMN) submarine fleet remains modest—comprising only two Scorpène-class diesel-electric attack submarines—these assets function as a force multiplier, vastly amplifying Malaysia’s surveillance, deterrence, and strike options across its extensive Exclusive Economic Zone (EEZ).

Both submarines are based at the Sepanggar Naval Base in Sabah, an operationally significant location adjacent to contested South China Sea waters and strategically close to vital international sea lanes.

KD Tunku Abdul Rahman, commissioned in 2009, carries advanced sonar arrays, French-designed combat management systems, and a weapons loadout that includes Italian Black Shark heavyweight torpedoes and French-made Exocet SM-39 submarine-launched anti-ship missiles, making it lethal against both surface and underwater threats.

KD Tun Abdul Razak, inducted into service in 2010, mirrors these capabilities and underscored the fleet’s growing combat credibility during Exercise Taming Sari 23/25 in July 2025, when it successfully executed Malaysia’s first live firing of a fully armed Black Shark torpedo in the South China Sea—a bold operational signal of RMN’s underwater strike readiness.

Each Scorpène-class submarine displaces 1,850 tons, measures 67.6 meters in length, and is capable of diving beyond 300 meters, enabling it to operate undetected in contested waters where stealth and surprise confer overwhelming advantage.

With the ability to carry up to 18 weapons—including a mix of torpedoes and anti-ship missiles—the RMN’s submarines provide a credible sea-denial capability against both state and non-state maritime threats.

Recognizing the need to preserve long-term readiness, Malaysia awarded a RM1.02 billion (USD 241 million) five-year Integrated Logistics Support and maintenance contract to BHIC Submarine Engineering Services at LIMA 2025.

This deal ensures that the Scorpène fleet will remain operationally viable into the next decade, sustaining Malaysia’s deterrence posture at a time when submarine activity across the Indo-Pacific is reaching unprecedented levels.

Beyond maintenance, Malaysia has placed increasing emphasis on building indigenous expertise in submarine engineering, training, and logistics, reducing dependency on foreign contractors for lifecycle support.

While there are currently no official plans to acquire additional submarines, ongoing debates within defence circles highlight the limitations of a two-submarine fleet, particularly when one vessel is in refit or maintenance, leaving only a single hull available for operations.

By contrast, neighbors such as Singapore and Vietnam are expanding their undersea fleets with new-generation platforms, while Indonesia has publicly announced ambitions for a fleet of at least 12 submarines by 2030.

This widening gap places Malaysia in a delicate position, balancing resource constraints with the need to keep pace in a region where undersea warfare is increasingly central to deterrence and power projection.

In response, Kuala Lumpur has focused on enhanced readiness, crew training, and forward deployment in Sabah, ensuring its submarines remain active in patrols that reinforce sovereignty claims over maritime features and sea lines of communication.

The RMN has also deepened cooperation with friendly navies, including submarine rescue frameworks such as the latest arrangement with Singapore, which enhances survivability and interoperability in the event of a submarine accident.

From a strategic lens, Malaysia’s limited submarine fleet remains valuable not for numbers but for the uncertainty it creates among potential adversaries, embodying the principle of “fleet-in-being” deterrence.

As the Indo-Pacific continues to tilt toward submarine-heavy deployments by major powers—including China’s expanding nuclear fleet, the U.S. Navy’s forward-based attack submarines, and Australia’s upcoming AUKUS-class nuclear boats—Malaysia’s ability to sustain, modernize, and strategically deploy its pair of Scorpènes will remain critical for its national defence and maritime sovereignty.

Singapore’s Submarine Force: Technological Edge

In stark contrast to Malaysia’s modest undersea arm, Singapore has embarked on an ambitious long-term modernization drive to build one of the most advanced submarine fleets in Southeast Asia.

The Republic of Singapore Navy (RSN) sees submarines as the ultimate guarantor of maritime security, reflecting the island state’s doctrine of technological superiority over numerical advantage.

With its small size and lack of strategic depth, Singapore has consistently relied on cutting-edge technology to offset vulnerabilities, and its submarine force has become the most potent expression of this strategy.

The RSN currently operates two Archer-class (Type Västergötland) submarines—RSS Archer and RSS Swordsman—both acquired from Sweden and refitted with Air-Independent Propulsion (AIP) systems, enabling weeks of submerged endurance far beyond conventional diesel-electric submarines.

It also retains two older Challenger-class (Type Sjöormen) boats—RSS Conqueror and RSS Chieftain—originally purchased in the 1990s, though these legacy platforms are being phased out as the Invincible-class takes over frontline duties.

At the core of Singapore’s modernization is the Invincible-class (Type 218SG) program, a bespoke design from Germany’s thyssenkrupp Marine Systems (tkMS) tailored to meet Singapore’s specific operational needs.

RSS Invincible entered service in 2023, followed by RSS Impeccable in 2024, with RSS Illustrious due in late 2025 and RSS Inimitable expected in 2026, marking a generational shift in the RSN’s undersea capability.

Each Invincible-class submarine displaces 2,200 tons, measures 70 meters, and incorporates state-of-the-art AIP technology, advanced stealth coatings, and noise-reduction systems that make it exceptionally hard to detect in congested waters.

The class integrates high levels of automation, reducing crew fatigue and enabling longer deployments, while also being compatible with unmanned underwater vehicles (UUVs) for reconnaissance, mine warfare, and special operations support.

These attributes give Singapore unmatched survivability, endurance, and lethality, enabling the RSN to dominate critical chokepoints such as the Singapore Strait and Malacca Strait, both of which are vital arteries for global trade and naval transit.

The Invincible-class is armed with heavyweight torpedoes and submarine-launched missiles, including the capability to fire anti-ship missiles such as the Harpoon Block II, with provisions for future upgrades to more advanced missile systems.

The design also incorporates modular payload bays, which analysts believe could in future accommodate cruise missiles or even hypersonic strike weapons, potentially elevating the RSN into the league of navies with long-range precision strike capability.

In March 2025, Singapore announced the procurement of two additional Invincible-class submarines, expanding the fleet to six by the mid-2030s in what amounts to one of the most ambitious undersea force renewals in ASEAN.

This move, formalized with tkMS in May 2025, ensures that Singapore will not only replace its Challenger and Archer classes but also field a next-generation submarine fleet larger than that of most of its regional peers.

By the mid-2030s, the RSN will operate six fully modern Invincible-class boats, making it the most advanced conventional submarine fleet in Southeast Asia and one of the most capable in the wider Indo-Pacific.

The RSN has also invested heavily in training, rescue, and support infrastructure, including the Submarine Training Centre and Submarine Support and Rescue Vessel (SSRV), ensuring operational resilience and safety.

Singapore’s close defence partnerships with Germany, Sweden, and the United States also ensure a steady transfer of advanced technology and tactics, further sharpening its undersea warfighting edge.

Strategically, the expansion of Singapore’s submarine fleet comes at a time of intensifying submarine activity in the region, with China’s People’s Liberation Army Navy (PLAN) expanding its nuclear-powered fleet and Indonesia announcing plans for 12 submarines by 2030.

By doubling down on submarine modernization, Singapore positions itself as a regional undersea power, capable not only of defending its maritime approaches but also of deterring and shaping the balance of power in contested waterways.

This technological overmatch also serves as a signal to extra-regional powers—the United States, Japan, Australia, and China—that Singapore is determined to retain freedom of action and safeguard the sea lines of communication (SLOCs) that underpin its survival as a trading nation.

Ultimately, Singapore’s Invincible-class fleet ensures that while it may lack geographic depth, it more than compensates with technological depth, cementing its status as Southeast Asia’s most formidable undersea operator well into the 2030s.

Strategic Impact

The Malaysia–Singapore submarine rescue pact is far more than a technical arrangement—it represents a geo-strategic alignment at a moment when undersea warfare is redefining the security landscape of the Indo-Pacific.

China’s People’s Liberation Army Navy (PLAN) is rapidly transforming into a blue-water force, expanding its fleet of nuclear-powered attack submarines (SSNs) and ballistic missile submarines (SSBNs) capable of projecting power deep into the Pacific and Indian Oceans.

Beijing currently operates at least six Type 094 (Jin-class) SSBNs armed with JL-2 submarine-launched ballistic missiles (SLBMs), and is introducing the next-generation Type 096 SSBN equipped with the longer-range JL-3 SLBMs, extending nuclear strike coverage well beyond Asia into continental North America.

Its nuclear-powered attack submarines, including the Type 093 Shang-class and the under-development Type 095 SSN, provide persistent undersea presence in the South China Sea, raising the stakes for all regional actors.

Meanwhile, the United States maintains forward-deployed Los Angeles, Virginia, and Seawolf-class SSNs out of Guam and Japan, ensuring dominance in intelligence gathering, anti-submarine warfare (ASW), and sea-denial operations across contested waters.

Japan has built up a formidable conventional submarine fleet with its Sōryū-class and new Taigei-class submarines, both equipped with lithium-ion batteries for unmatched submerged endurance, underscoring Tokyo’s determination to counterbalance China’s advances.

Australia, under the AUKUS agreement, will introduce nuclear-powered SSNs by the 2030s, giving Canberra unprecedented reach and permanently altering the balance of power in the Indo-Pacific undersea domain.

India, with its Arihant-class SSBNs and expanding fleet of Scorpène-class attack submarines, is also pushing forward undersea deterrence capabilities, adding another layer of complexity to the Indo-Pacific submarine equation.

Within this environment, the Malaysia–Singapore pact signals that ASEAN states are no longer content to be passive observers but are actively shaping their roles in undersea security architecture.

By harmonizing rescue frameworks and establishing joint submarine escape and rescue (SMER) protocols, Kuala Lumpur and Singapore are ensuring that their limited but strategically important submarine fleets are integrated into a wider safety and operational network.

This agreement provides both nations with interoperability in crisis management, a critical factor given the risks of accidents, collisions, or technical failures in congested maritime chokepoints such as the Malacca Strait and South China Sea.

It embeds submarine rescue readiness into the broader ASEAN security fabric, complementing existing cooperative mechanisms such as the ASEAN Defence Ministers’ Meeting Plus (ADMM-Plus) framework that often involves joint submarine rescue drills with external powers like the United States, Japan, and South Korea.

The pact also carries an important diplomatic message—that even nations with relatively small submarine fleets understand the existential risk posed by undersea incidents, and are willing to pool resources to enhance survivability and resilience.

Strategically, this agreement strengthens Southeast Asia’s credibility as an active security stakeholder, signaling to extra-regional powers that the region is preparing for a future in which submarine activity is central to both deterrence and escalation risks.

It also reflects the reality that undersea warfare—silent, stealthy, and potentially catastrophic—has become a decisive factor in Asia’s balance of power, as nations race to deploy more advanced submarines, longer-range SLBMs, and increasingly sophisticated anti-submarine warfare networks.

For Malaysia and Singapore, this pact may appear limited in scope, but its implications are profound: it represents a step toward ASEAN’s evolution from a defensive grouping to a more proactive security actor in the Indo-Pacific undersea domain.

— DEFENCE SECURITY ASIA