SINGAPORE: Deploying heavily armed, grey-hulled warships to tackle every maritime security threat along important sea lanes is akin to taking a hammer to every problem, defence experts said, adding that increasingly complex challenges call for more measured responses at sea.

Earlier this month, the Republic of Singapore Navy (RSN) launched its first Sentinel-class offshore patrol vessel, christened Sentinel. It is the first of four government vessels built to meet a broader spectrum of maritime security operations.

Their calibrated capabilities will allow Singapore to respond to incidents in a measured and proportionate manner, giving the government "more options" at sea, the Ministry of Defence (MINDEF) said during the vessel’s launch.

They offer an alternative to conventional warships, said Mr Nicholas Lim, senior fellow and coordinator of defence and military relations at the S Rajaratnam School of International Studies (RSIS) in Nanyang Technological University.

Unlike the standard grey hull on most combatant and auxiliary surface ships that keeps them camouflaged against the marine backdrop, the offshore patrol vessels sport white hulls.

"You cannot deploy your grey-hulled warships for everything. It's like you're using a hammer for every single problem," said Mr Lim.

Regional countries have made similar moves. In 2024, Malaysia's Maritime Enforcement Agency took delivery of a new offshore patrol vessel while the Indonesian navy launched two such ships.

Unlike the heavily militarised environment in the Middle East, the sea lanes around Singapore face a different breed of risk, experts said.

From maritime terrorism and trafficking to drones and threats to undersea infrastructure, modern navies in the region must manage risks that sit in the ambiguous grey zone between routine law enforcement and conventional warfare.

More than just dealing with piracy and sea robbery, navies need to respond to different types of security challenges, said Mr Lim.

Recent tensions across vital global choke points like the Strait of Hormuz demonstrated the urgent demand for vessels that can deter threats and defuse flashpoints before they disrupt international trade.

Like the Strait of Hormuz, the Straits of Malacca and Singapore are among the world's most important shipping routes, carrying nearly a quarter of global seaborne trade and almost a third of global oil and gas supplies. But their geopolitical and security environments are worlds apart, experts stressed.

Maritime security in the Strait of Hormuz is closely intertwined with broader military and geopolitical tensions, said associate research fellow from the RSIS' maritime security programme Chong De Xian.

"In contrast, the Straits of Malacca and Singapore operate in a relatively stable security environment, where the littoral states share a strong interest in keeping the waterways open and secure," he added, referring to Indonesia, Malaysia and Singapore.

Lessons from Hormuz Beyond these threats, geopolitical tensions and armed conflict have exposed the vulnerability of international shipping routes.

The Strait of Hormuz carried about one-fifth of the world's energy shipments before the war between the United States and Iran began earlier this year.

On Oct 14, two Singapore-registered container vessels were struck by unknown projectiles while transiting the strait. One sank after sustaining damage and catching fire. It was the second vessel to sink since the war began on Feb 28, according to the International Maritime Organization.

Meanwhile, reports emerged in September that the Iranian-backed Houthi rebel group had taken control of Yemen's entire Red Sea coast and advanced onto islands in the Bab al-Mandeb Strait.

The narrow waterway at the southern tip of the Red Sea, which serves as a gateway to the Suez Canal from the Indian Ocean, is a key shipping route and an alternative for the world's largest oil exporter Saudi Arabia to export crude oil.

Such developments show how threats to commercial shipping can disrupt international trade and energy flows even without physically closing maritime chokepoints, Mr Chong said. However, experts cautioned against drawing direct comparisons with the Straits of Malacca and Singapore. "The two situations are not comparable," said Dr Storey.

"The most important difference between the two is that in Southeast Asia the littoral states are committed to keeping the Straits of Malacca and Singapore free, open and safe for international shipping while Iran has weaponised the Strait of Hormuz." Mr Lim similarly pointed to the strong cooperation among Singapore, Malaysia and Indonesia, which share an interest in keeping the waterways open.

He said the situation in the Strait of Hormuz nevertheless offered an important lesson on the need to uphold international law, particularly the United Nations Convention on the Law of the Sea (UNCLOS), a set of rules that governs the world's oceans.

It allocates rights and legal authority to states, and establishes regulations for the peaceful use of the sea and its resources.

"The one big lesson learnt from the Strait of Hormuz is that we cannot take it for granted that access is always there. We have to protect this UNCLOS to ensure that the key international straits are open," he said.

But he was confident that a similar situation would not unfold in the Straits of Malacca and Singapore, given the differences in geography, history, culture and shared interests. Collapse The launch of Singapore's first Sentinel-class Offshore Patrol Vessel on Oct 1, 2026.

HOW MARITIME THREATS HAVE EVOLVED Today, regional threats at sea include illegal fishing, smuggling and maritime terrorism, said Mr Lim, who served in the RSN for about 30 years before retiring as a colonel last year.

Fishing vessels, for instance, can be exploited to transport drugs or be used for smuggling, while maritime terrorism could involve the hijacking of liquefied natural gas (LNG) carriers and turning them into potential "floating bombs".

While piracy and armed robbery incidents remain ever-present concerns in the Straits of Malacca and Singapore, Mr Lim said the numbers fluctuate based on enforcement drives and weather patterns.

"We do not have any serious kind of piracy or sea robbery incidents. By serious I mean (the) hijacking of entire ships. We have not seen that, fingers crossed, for many, many years," he said, crediting the coordinated efforts of Singapore, Malaysia and Indonesia.

Dr Ian Storey, principal fellow at the ISEAS-Yusof Ishak Institute, agreed that piracy and sea robbery have been effectively managed, with closer cooperation among the three countries' navies and law enforcement agencies significantly reducing maritime crime over the past two decades.

Nonetheless, Southeast Asia's wider maritime security landscape presents a "mixed picture", he said.

Transnational trafficking in narcotics, weapons as well as people still persist, alongside longstanding territorial disputes and overlapping maritime boundaries that continue to generate tensions, particularly in the South China Sea. Technological shifts can also expose new vulnerabilities, said experts.

The proliferation of aerial and underwater drones poses an increasing threat to the region, while critical infrastructure, including undersea cables and energy pipelines, remains vulnerable to both accidents and sabotage, Dr Storey said.

Because undersea assets are spread across vast seabed tracts, protecting them from deliberate foul play is difficult.

What complicates efforts are the geographical challenges and evidential difficulties in proving deliberate interference, said RSIS’ Mr Chong.

Such disruptions to critical maritime infrastructure can have far-reaching economic and security consequences, he said.

Hegave examples of how cyberattacks could disrupt port and shipping operations and manipulate vessel-tracking information so as to compromise navigational safety.

Illicit maritime activities have also become more sophisticated, with deceptive shipping practices, sanctions evasion and shadow fleets making surveillance and enforcement harder, he added.

RESPONDING WITHOUT ESCALATION Singapore's location alongside one of the world's busiest shipping routes, and its reliance on maritime trade and essential supplies, have always presented particular challenges for the RSN, said Mr Chong, himself a former RSN officer.

"Such situations require responses that are appropriate and proportionate to the circumstances. Some incidents may be resolved through warnings and other less-lethal measures, while others may require more forceful intervention." Having a wider range of capabilities allows maritime security forces to take graduated responses as situations develop, without prematurely resorting to more forceful options, he said.

"This is particularly important in Singapore’s congested maritime environment where incidents must be managed without unnecessarily disrupting commercial shipping or escalating tensions." There can also be significant political and diplomatic implications, especially when foreign vessels are involved.

"Dedicated maritime security vessels with a less militaristic posture compared to conventional warships further support this approach by allowing Singapore to protect its maritime interests while minimising the risk of escalation," Mr Chong said.

The growing complexity of maritime security threats has also placed greater demands on navies to manage incidents that fall between routine law enforcement and conventional naval warfare, he added. The vessels' white hulls are significant in this regard.

White hulls and red racing stripes are in line with vessels operated by maritime security agencies around the world, Mindef previously said.

Unlike the grey hulls traditionally associated with heavily armed warships, white-hulled vessels are seen as less threatening or provocative, Dr Storey said.

Mr Lim similarly noted that conventional warships with their grey hulls carry a "certain signature" that may be unnecessary for some maritime security operations. Raising an example of a sea robbery, he said there is no need to deploy a warship to deal with a pirate boat.

"Can't you just use, for example, an offshore patrol vessel that's big enough, that has the manpower and the equipment to deal with it? Why do you need to send an advanced warship with missiles to deal with a pirate boat?"

STAYING POWER Singapore's new offshore patrol vessel will “inherit” the maritime security missions of the existing Sentinel-class Maritime Security and Response Vessels (MSRVs) while also safeguarding the country's territorial waters, said Mindef when the vessels were launched.

The MSRVs were also touted to provide more calibrated options to respond to maritime incidents. While they also have grey-coloured hulls, the MSRVs all bear a red “racing” stripe on their bow.

While these responsibilities remain largely unchanged, the new offshore patrol vessels offer enhanced capabilities and a wider range of options to take on these missions, Mr Chong said.

For instance, responding to a suspicious or non-compliant vessel may require first establishing its identity and intentions, issuing warnings and intercepting it before more forceful intervention becomes necessary.

The offshore patrol vessel can deploy smaller craft for closer investigation or intervention as situations develop.

They are also equipped to address emerging threats. Their weapons suite features the STRALES guided gun, which enables the vessels to counter unmanned threats, Mr Chong noted.

The vessels could also support other agencies in responding to suspicious activities near sensitive maritime installations Their greater endurance would allow them to maintain a more sustained presence at sea.

The offshore patrol vessels have more than five times the displacement of the existing MSRVs and are designed for longer operations.

Each of the new vessels has a displacement of 2,700 tonnes, measures 94.85m long and 15.2m wide, and carries a baseline crew of about 40.

In comparison, the MSRVs have a displacement of 525 tonnes, measure 55m long and 8.6m wide, and carry a baseline crew of about 30.

The existing vessels have an endurance of 1,800 nautical miles, compared with more than 4,000 nautical miles for the new vessels, allowing the latter to travel farther without refuelling or resupply.

But their increased size and endurance do not necessarily signal an expansion of Singapore's maritime security operations farther from home, experts said.

Instead, they offer the RSN greater flexibility to remain at sea longer and for extended periods.

"While their enhanced capabilities provide the option of operating farther offshore when required, they are equally valuable for maintaining a more persistent maritime security presence closer to home," Mr Chong said.

Ultimately, the new vessels reflect the need for maritime security forces to adapt to grey-zone threats, ensuring that Singapore, as well as its regional partners, can protect vital waterways without reaching for a sledgehammer.