(DEFENCE SECURITY ASIA) — The Philippines has yet to award a contract for its first submarines, but its search for two diesel-electric attack boats has become a consequential test of how Manila intends to defend an archipelago exposed to pressure in the South China Sea.

Under the Armed Forces of the Philippines’ Re-Horizon 3 modernization program, the requirement extends beyond two hulls to a submarine base, crew training, maintenance facilities and long-term support, making the decision as much about building an institution as buying weapons.

The prospective package has been discussed at roughly $1.4 billion to $2.0 billion, although the final cost will depend on financing, weapons, infrastructure and support terms that remain unsettled because Manila has named neither a preferred bidder nor a winning design.

President Ferdinand Marcos Jr.’s government has advanced the effort amid growing friction with China in the West Philippine Sea, yet even an early contract would leave Manila several years from receiving a boat and longer still from sustaining credible patrols.

Hanwha Ocean, HD Hyundai Heavy Industries, France’s Naval Group, Spain’s Navantia and an Italian-German team led by Fincantieri are pursuing different routes into the program, with their industrial footprints and financing proposals potentially carrying as much weight as submarine performance.

Hanwha’s chairman described the proposed acquisition as a “complete force” during the company’s campaign, a phrase that captures Manila’s central problem: an unfamiliar platform cannot deliver deterrence without qualified crews, secure berths, rescue arrangements and reliable maintenance.

HD Hyundai Heavy Industries officials have voiced a “strong chance” of competing successfully, reflecting the company’s existing Philippine shipbuilding relationship and its position at Subic, where local facilities could reduce some of the infrastructure work required for an initial submarine service.

Navantia’s proposed deferred-payment arrangement and alternative base at Ormoc illustrate a different trade-off, offering Manila a financing path while potentially separating its submarines from the naval infrastructure that several competitors expect to develop around Subic.

The geopolitical stakes extend beyond procurement because the Philippines lies between the South China Sea and the Philippine Sea, near passages whose control would matter during a regional conflict involving Chinese surface forces, allied units or Taiwan.

A small Philippine submarine fleet could complicate hostile wartime movement through selected approaches, but two boats would neither patrol the entire maritime domain continuously nor resolve the coercive encounters involving coast guards and militia vessels that Manila faces today.

China’s response, alliance coordination and the seller’s long-term commitment will therefore shape the program’s effect alongside sonar, propulsion and weapons choices, while any assertion that the purchase would decisively alter the regional balance remains premature without a contract or trained force.

For Manila, the decisive question is whether a future boat can leave a survivable base, receive useful targeting information and operate alongside coastal missiles, mines and surface forces when required, rather than whether a design looks imposing in a bid presentation.

(CLICK): Philippines Pushes for Dream Submarines as Global Defense Giants Battle for the Deal

Five Offers, Five Ways to Build a Submarine Force

Hanwha Ocean is promoting a Philippine version of South Korea’s KSS-III submarine alongside a smaller Ocean 1400 option, giving Manila a choice between a more ambitious undersea platform and a design likely to impose a lighter initial operating burden.

The proposed KSS-III PN is described as a roughly 2,800-ton diesel-electric boat with lithium-ion batteries and six torpedo tubes, but the Philippine configuration under discussion lacks the vertical-launch cells and air-independent propulsion associated with other versions of the wider family.

That distinction matters because analysts cannot treat every KSS-III capability as part of Manila’s prospective purchase; battery endurance, missile options, combat-system integration and the location of major overhaul work would depend on the configuration eventually written into a contract.

Hanwha’s smaller Ocean 1400 proposal draws on the Type 209 and Chang Bogo lineage, potentially easing crew development and local maintenance, although a lower entry burden would also give Manila a different combination of payload, internal space and upgrade capacity.

HD Hyundai Heavy Industries is advancing a medium submarine concept commonly identified as HDS-2300 while other larger options have been discussed, but the precise Philippine configuration and financing terms are less clearly defined than its existing industrial presence at Subic.

The company’s Agila Subic yard and established relationship with the Philippine Navy could help connect hull support with domestic facilities, yet operating a shipyard does not by itself establish the certified procedures, trained workforce and rescue arrangements required for submarines.

Naval Group’s Scorpène proposal combines a mature export family with plans for training and facilities around Subic, although the exact Philippine combination of batteries, air-independent propulsion and weapons has not been publicly fixed in a final purchase agreement.

Navantia is offering two S-80 Plus boats with training, technology transfer and a proposed support base at Ormoc, positioning financing and shore infrastructure as central selling points for one of the largest conventional submarine designs in the contest.

Fincantieri and Germany’s TKMS are promoting the U212 Near Future Submarine with fuel-cell air-independent propulsion and lithium-ion batteries, emphasizing acoustic discretion, shallow-water operations and Italian-backed training, while the precise export configuration remains subject to negotiation.

None of these proposals should be mistaken for an awarded contract: advertised endurance, shallow-water performance, local jobs and payment terms are bid attributes whose operational value depends on negotiated specifications, testing, infrastructure completion and sustained Philippine funding.

(CLICK): Philippine Navy Plans to Enhance Capabilities to Detect Foreign Submarines

The Base and the Budget May Decide the Contest

A first submarine acquisition creates a permanent logistics commitment because batteries, propulsion components, weapons handling, docking cycles and specialist personnel must remain available long after the political attention surrounding a contract announcement has faded.

Subic features prominently in several proposals and already attracts naval and industrial investment, giving it practical advantages for training and repair, but concentrating boats, equipment and personnel there would also create a conspicuous wartime target.

Navantia’s Ormoc proposal offers a different geographic answer, with a purpose-built base and maintenance infrastructure, although a separate site could demand additional investment to connect submarine operations with the Philippine Navy’s emerging support network.

Financing could determine which design Manila can realistically field because deferred payments or sovereign-backed loans change when costs fall due, while the eventual budget must still absorb crew training, ammunition, refits and facilities over decades.

Spanish material has presented an approximately $1.7 billion package and payments beginning after initial delivery, whereas other bidders have discussed state-backed or facilitated financing; the proposals cannot be compared reliably without identical assumptions about equipment and lifetime support.

A modern lithium-ion submarine requires battery safety practices and specialist repair capacity, while an air-independent propulsion system introduces its own supply and maintenance demands, so endurance claims must be weighed against the readiness Manila can sustain ashore.

The first Filipino crews will also need a training pipeline extending beyond basic ship handling into acoustic classification, weapons employment, emergency procedures and command judgment, making foreign instruction an operational dependency during the force’s formative years.

Submarine rescue arrangements are particularly consequential for a new operator because safe operations depend on rehearsed emergency response, compatible equipment and access to partners, none of which can be inferred from a design’s advertised displacement or weapons fit.

Technology transfer can strengthen local maintenance and reduce reliance on overseas yards, but its military value depends on which tasks Philippine personnel may perform, whether parts remain accessible and how quickly domestic facilities achieve dependable standards.

Manila’s strongest negotiating position will come from comparing each complete force package against a realistic deployment schedule, since a cheaper hull that waits for a pier, crew or battery workshop could deliver less deterrence than a costlier supported boat.

(CLICK): Philippines Detects Russian Submarine Operating in South China Sea Near Its Waters

Why Two Submarines Matter Near Luzon and Palawan

Philippine geography gives a small submarine force potential influence disproportionate to its numbers because Luzon, Palawan and nearby islands border routes connecting contested South China Sea waters with approaches to the wider Pacific.

The Luzon Strait and Bashi Channel are particularly consequential in a Taiwan contingency, when naval movements between the South China Sea and Philippine Sea could place a premium on surveillance, sea denial and the protection of military access.

Farther south, approaches near Palawan and Balabac create other operating areas where a diesel-electric submarine could wait for surface forces, collect acoustic information or threaten shipping during war, provided its crew receives usable intelligence and clear orders.

Quiet propulsion, capable sonar and heavyweight torpedoes would force an adversary to consider an underwater threat in selected waters, potentially diverting helicopters, escorts and other anti-submarine resources even when a Philippine boat is not actually present.

That effect is conditional rather than automatic, because submarines have limited speed, finite patrol endurance and uncertain awareness outside their sensor range, while geography alone cannot compensate for weak reconnaissance or gaps in communications.

A submarine could complement Philippine coastal missiles and mines by adding uncertainty below the surface, requiring hostile commanders to plan against several distinct threats whose locations and readiness they may be unable to establish confidently.

The same operating concept makes force availability critical: with only two hulls, maintenance and training could leave a single boat available for deployment, limiting how many passages Manila can monitor or threaten at one time.

Claims that Philippine submarines would seal the Luzon Strait therefore overstate what the proposed fleet could accomplish; any wider denial effort would depend on coordinated aircraft, shore sensors, missiles, allied forces and sustained logistics.

Manila would also retain political control over its boats, meaning their employment in a Taiwan-related conflict could not be presumed merely from closer defence cooperation with the United States or shared concern about regional access.

The plausible strategic gain is narrower but still significant: a competent Philippine submarine service could make selected approaches harder to use in wartime while giving Manila an independent military option beneath waters central to its own defence.

China’s Submarine Force Raises the Stakes Near the Philippines

China’s submarine force gives the People’s Liberation Army Navy an underwater dimension in the South China Sea, where boats operating from bases on Hainan could support surveillance, sea denial and nuclear deterrence across waters connected to the Philippine archipelago.

Chinese attack submarines would pose a different problem from the coast-guard and maritime militia vessels Manila encounters around disputed features, because a submerged boat could threaten naval reinforcements or gather intelligence without creating the visible confrontation typical of peacetime coercion.

For Philippine planners, the operational concern extends beyond waters west of Palawan to the Luzon Strait, where submarine movements between the South China Sea and Philippine Sea could affect access during a wider crisis involving Taiwan or allied forces.

China’s Jin-class ballistic-missile submarines add a separate strategic consideration, since their nuclear-deterrent mission could increase Beijing’s interest in protecting operating areas connected to the South China Sea, although publicly available information cannot establish where individual boats patrol.

A Philippine diesel-electric submarine would not be expected to match China’s larger undersea force boat for boat, but it could introduce uncertainty near selected approaches by compelling Chinese commanders to account for a concealed torpedo threat alongside coastal missiles and mines.

That uncertainty would depend on acoustic conditions, crew proficiency and external cueing, because a Philippine boat without reliable surveillance support could struggle to locate a target before Chinese anti-submarine aircraft, helicopters or surface escorts constrained its freedom of movement.

The same imbalance would complicate protection of a future Philippine submarine base, where maintenance facilities and boats alongside would be more readily located than a deployed vessel, making infrastructure resilience central to any credible wartime force posture.

China’s submarine infrastructure on Hainan does not establish that a particular boat is patrolling near Philippine waters on any given day, since operational movements are rarely disclosed and geography identifies possible routes rather than confirmed positions.

A contest between Philippine and Chinese submarines would therefore be shaped by intelligence, logistics and anti-submarine warfare as much as hull numbers, with each side seeking to protect its own boats while making the other uncertain about underwater access.

For Manila, the strategic case for two submarines lies in adding a credible threat beneath selected maritime approaches; whether that threat changes Chinese wartime calculations will depend on sustained patrol readiness and integration with the Philippines’ wider archipelagic defence system.

China’s Gray-Zone Pressure Exposes a Hard Limit

The procurement’s most immediate limitation is that submarines cannot escort resupply missions, document collisions or physically protect crews confronting water cannons and maritime militia vessels in the day-to-day disputes Manila currently faces.

Those encounters involve visibility, persistence and control of escalation around contested features, whereas a submerged attack boat is designed for covert surveillance and wartime sea denial rather than public enforcement of maritime claims.

BrahMos coastal missiles, surveillance drones, coast-guard ships and legal instruments consequently address different parts of Manila’s present challenge, leaving submarines valuable chiefly if coercion escalates into blockade, strikes or sustained naval combat.

A future Philippine boat might complicate Chinese surface operations during such a conflict, but its purchase alone would not dislodge forces from disputed positions or prevent further coercive activity below the threshold of war.

China could also respond politically to a contract by portraying the acquisition as part of a wider allied military buildup, although the scale and form of any resulting diplomatic or maritime pressure cannot be predicted from the bids.

For Beijing’s wartime planners, the harder question would be whether a Philippine submarine is at sea near an intended route, forcing a search effort that consumes time and anti-submarine assets without guaranteeing contact.

That uncertainty depends on credibility: a force known to suffer maintenance delays, restricted training or predictable sailing patterns would impose a smaller planning burden than two boats able to deploy safely and without advance notice.

The Philippines would face a parallel escalation problem if a submarine tracked or threatened Chinese forces during a crisis, because covert operations can increase military leverage while leaving political leaders less time to interpret an underwater encounter.

Accident and misidentification risks would also rise as another operator enters busy regional waters, strengthening the case for rescue coordination and practical procedures that allow forces to manage incidents without revealing sensitive patrol plans.

Manila should therefore judge the acquisition against a specific wartime mission, while maintaining separate investments for the visible maritime contest; using submarine deterrence to promise relief from everyday harassment would create expectations the platform cannot meet.

The Seller, Allies and Long-Term Force Posture

The winning bidder would become a long-term participant in Philippine undersea capability through training, spare parts and technical support, giving Seoul, Paris, Madrid or Rome a continuing stake in the program’s success.

A Korean award would deepen an established naval shipbuilding relationship, while a European award would bring another defence industry into Philippine submarine operations; neither outcome would itself commit the supplier country to intervene in a conflict.

Washington has no manned-submarine proposal identified in the supplied account, yet a Philippine force could create opportunities for acoustic cooperation, exercises and rescue planning alongside broader United States access and maritime-security activity.

Japan and Australia could likewise become useful training or coordination partners, although interoperability would require agreed procedures and compatible systems rather than follow automatically from operating friendly submarines in the same region.

Across Southeast Asia, several navies already operate conventional submarines, so a Philippine purchase would fill a conspicuous capability gap without proving that a new regional submarine race had begun.

The comparison with Vietnam is instructive but limited: a larger submarine inventory can complicate an opponent’s naval planning without reversing contested territorial control, and Manila’s proposed two-boat force would face an even tighter availability constraint.

For Philippine planners, the most important comparison among bidders is therefore how each would sustain patrols after delivery, especially when major maintenance competes with crew qualification and other modernization demands for scarce funding.

An award would send a political signal before a submarine entered service, but operational deterrence would emerge only as Manila demonstrated safe deployments, credible weapons integration and the ability to restore readiness after routine defects.

Conversely, an underfunded base or training program could turn an expensive acquisition into a vulnerable shore-bound asset, while also making the country more dependent on foreign repair capacity during a crisis.

The Philippines’ submarine decision will reshape regional calculations only if two boats become part of a durable archipelagic defence system, supported by people, infrastructure, sensors and clear command decisions that make an underwater threat credible.