Singapore – Submarines remain a decisive factor in modern naval warfare, providing stealth, deterrence, and intelligence-gathering capabilities beneath the world’s oceans. According to the Global Firepower Index 2025, seven nations lead the global submarine count, with the United States topping the list and India ranking seventh.
In naval terms, submarine fleets typically comprise three categories: nuclear-powered ballistic missile submarines (SSBNs) designed for strategic deterrence, nuclear-powered attack submarines (SSNs) for anti-ship and anti-submarine missions, and cruise missile submarines (SSGNs) capable of precision land strikes. Diesel-electric attack submarines (SSKs) remain a cost-effective option for many navies, offering quiet operation in coastal and regional waters.
United States – 70 submarines
The United States Navy operates the world’s largest submarine fleet, all nuclear-powered, spanning SSBNs, SSNs, and SSGNs. Its focus on technological superiority ensures unmatched capabilities in stealth, weapons systems, and undersea endurance.
Russia – 63 submarines
Russia holds the second-largest fleet, combining nuclear and diesel-electric submarines. Continuous modernization efforts aim to enhance both strategic deterrence and regional combat readiness.
China – 61 submarines
China’s expanding submarine fleet ranks third, with nuclear and diesel-electric platforms supporting its growing Indo-Pacific presence and long-range maritime operations.
Iran – 25 submarines
Iran ranks fourth, fielding a mix of compact midget submarines and standard attack boats, primarily for regional defense and asymmetric warfare in the Persian Gulf.
Japan – 24 submarines
Japan’s diesel-electric fleet, ranked fifth, is recognized for its advanced quieting technology and operational efficiency, optimized for Asia-Pacific maritime security.
South Korea – 22 submarines
In sixth place, South Korea’s submarine force is modernizing rapidly, adding new designs to reinforce its deterrence posture against regional threats.
India – 18 submarines
India ranks seventh, operating nuclear-powered ballistic missile submarines and diesel-electric attack boats. The Indian Navy continues to enhance its undersea capabilities to protect sea lanes and strengthen deterrence in the Indian Ocean.
As maritime competition intensifies, submarine fleets will remain a central measure of naval strength. Nations are investing in stealth technology, improved sonar, and advanced weapon systems to ensure operational dominance in an increasingly contested undersea domain.
