A new generation of submarines is emerging, and undersea operations and broader maritime strategy may never be the same. Saab’s A26, described as the first ‘fifth-generation’ conventional submarine, combines stealth, endurance, and modular flexibility in ways that challenge traditional assumptions about diesel-electric platforms. Designed as a multi-domain system, the A26 can conduct intelligence collection, deploy unmanned systems, support special operations, and monitor undersea infrastructure — all while remaining difficult to detect. Its design exemplifies how advanced conventional submarines can provide highly capable, lower-cost alternatives to nuclear-powered vessels, offering operational flexibility across multiple theatres and mission scenarios.

From Early Submarines to Fifth-Generation Design

The evolution of submarines over the past century traces a progressive expansion of operational reach, stealth, and mission versatility. Early 20th-century diesel-electric boats had limited submerged endurance, required surfacing for air and battery recharging, and carried rudimentary torpedoes.

Post-World War II developments improved hull designs, battery capacity, snorkels, and sensor systems, gradually extending submerged endurance and tactical options. Navies experimented with air-independent propulsion (AIP) concepts and modular mission layouts, paving the way for more capable conventional submarines. The introduction of nuclear propulsion in the 1950s marked a decisive leap: nuclear-powered submarines could sustain high speeds for extended periods, remain submerged for months, and strike at long distances, fundamentally altering the strategic calculus of undersea warfare.

Despite these advances, diesel-electric submarines retained certain advantages, including quieter acoustic signatures at low speeds, lower operating costs, and the ability to operate in shallow littoral waters where nuclear vessels were less suited. By the late 20th century, these vessels benefited from automation, hydrodynamic refinements, and improved sensors, yet remained constrained by limited energy supply. Air-independent propulsion (AIP) systems extended submerged endurance for conventional submarines, narrowing the gap with nuclear vessels and enabling new concepts for multi-domain operations.

The A26 embodies this evolution, integrating modular mission bays, advanced sonar, and sensor suites, noise-reduction technologies, and compatibility with unmanned systems—reflecting a shift toward versatile undersea influence rather than purely weapons-focused operations.

Technical and Operational Capabilities

Stealth is central to the A26’s design. Beyond conventional acoustic quieting, Saab employs hull shaping, specialized coatings, and electronic degaussing to minimize magnetic, electric, infrared, radar, and hydrodynamic signatures. Its Stirling-engine AIP allows weeks of submerged operation without surfacing, supporting persistent intelligence-gathering and covert missions.

The A26’s modular mission bay can deploy unmanned underwater vehicles (UUVs), special forces, divers, and seabed sensors. This flexibility enables the submarine to perform multiple roles simultaneously: monitoring undersea energy and communication infrastructure, conducting intelligence, surveillance, and reconnaissance (ISR), supporting special operations, and executing conventional weapons deployments. Its advanced communications architecture integrates the submarine with broader intelligence networks, linking undersea, cyber, and electromagnetic domains. This is increasingly relevant as global data flows through vulnerable submarine cables, allowing operators to monitor critical infrastructure while maintaining operational discretion in contested maritime zones.

UUV integration further extends operational reach. Submarines can deploy autonomous systems for seabed mapping, cable inspection, or reconnaissance of littoral zones without exposing the vessel itself. When paired with modular payloads, a single A26 can adapt to multiple mission sets, supporting grey-zone operations, distributed ISR, and allied coordination in ways earlier generations of conventional submarines could not.

Strategic Context: Europe

In European waters, the A26 can serve as a versatile instrument for situational awareness and deterrence. Russia continues to operate and modernize elements of its Northern and Baltic fleets, relying on both nuclear and diesel-electric submarines to secure strategic areas such as the Baltic Sea and approaches to the North Sea. Despite ongoing challenges—including ageing vessels, maintenance issues, and operational setbacks—the Russian navy remains active, signaling continued ambition in undersea operations.

A26-class submarines could covertly monitor these movements, map seabed infrastructure, and support intelligence collection for NATO and allied forces. Their endurance and low observability enable a persistent presence in contested littorals, while modular mission bays and UUV integration allow diverse operational profiles without over-reliance on nuclear-powered vessels. By giving middle powers the capacity to contribute to alliance operations, developments like the A26 strengthen distributed deterrence and regional maritime security.

Strategic Context: Indo-Pacific

While Europe presents one set of strategic pressures, the Indo-Pacific has seen its own accelerating undersea competition as multiple actors expand capabilities around strategic chokepoints and submarine cable networks. Straits such as Sunda, Malacca, and Lombok, along with undersea data lines linking Australia, Southeast Asia, and beyond, are increasingly central to regional security dynamics.

A26-class boats, potentially operated by regional partners, could conduct covert reconnaissance, deploy unmanned systems, and support special operations without relying on nuclear propulsion. Their versatility complicates undersea dominance calculations and provides operators with a range of options for intelligence collection, situational awareness, and deterrence. These capabilities reveal how advanced conventional submarines can balance operational reach, cost-effectiveness, and strategic flexibility in contested maritime environments.

Private and State Innovation Driving Naval Capabilities

Saab’s development of the A26 illustrates the marked role of private defense firms in accelerating undersea innovation. By combining GHOST (Genuine Holistic Stealth) technology, modular layouts, and Stirling-engine AIP, Saab achieves a level of flexibility and stealth that is difficult to match in larger, state-driven programs. Collaborations with hybrid AUV/ROVs, such as the Sabretooth, further enhance autonomous capabilities for reconnaissance and seabed operations.

Other private firms, including Germany’s ThyssenKrupp Marine Systems, also advance propulsion, modular mission bays, and unmanned systems, enabling governments to modernize forces and integrate cutting-edge technologies efficiently. State-owned companies, such as France’s Naval Group, contribute similarly, with submarines like the Barracuda (Suffren-class) nuclear attack submarines illustrating how state expertise drives advanced propulsion, weapons integration, and mission flexibility.

Together, private and state-owned firms act as strategic partners, shaping national and allied undersea capabilities. They facilitate the rapid integration of autonomous systems, sensor networks, and modular payloads, ensuring that conventional submarines remain relevant in a landscape increasingly defined by multi-domain threats and grey-zone competition.

Operational and Strategic Implications

The A26 is also a catalyst for technological development. Its integration of autonomous systems, broad-spectrum stealth, and modular payloads challenges existing anti-submarine warfare networks and encourages investment in next-generation detection technologies, distributed sensor grids, and AI-enabled monitoring tools. Programmes underway in countries such as the United States, Japan, and Germany illustrate how the arrival of advanced conventional submarines can shape broader defense planning and accelerate innovation across multiple domains.

Crucially, these developments demonstrate how middle powers can exert meaningful influence undersea without operating nuclear submarines. By combining modern propulsion, advanced sensors, and seamless integration into allied intelligence networks, vessels like the A26 allow smaller navies to improve situational awareness, support grey-zone operations, and contribute to distributed deterrence. This broadens the number of actors able to shape regional maritime security and deepens the collective resilience of allied networks in an increasingly contested undersea environment.

In an era of intensifying competition, rising crises, and heightened maritime tension, the A26 and similar submarines illustrate that undersea warfare is no longer the exclusive domain of nuclear powers. Advanced conventional submarines are poised to shape strategic, operational, and technological dimensions of global maritime security for decades to come.

Scott N. Romaniuk: Senior Research Fellow, Centre for Contemporary Asia Studies, Corvinus Institute for Advanced Studies (CIAS), Corvinus University of Budapest, Hungary.

László Csicsmann: Full Professor and Head of the Centre for Contemporary Asia Studies, Corvinus Institute for Advanced Studies (CIAS), Corvinus University of Budapest, Hungary; Senior Research Fellow, Hungarian Institute of International Affairs (HIIA).

Khandakar Tahmid Rejwan: Research Data Analyst, Bangladesh Peace Observatory, Centre for Alternatives (CA), Dhaka, Bangladesh.