Submarines represent one of the strategic properties that play important roles in modern warfare. Therefore, several military powers have invested in the development of submarines with new technologies and solutions to enhance their deterrence capabilities and gain superiority in modern warfare.

Developing new nuclear submarines and improving diesel-electric submarines

Given the importance of ballistic missile submarines and nuclear-powered attack submarines, military powers have promoted investment in developing these types of strategic equipment. In particular, nuclear submarines are capable of performing missions for several months without surfacing, so they are being integrated with extremely sophisticated combat systems, allowing for surveillance, reconnaissance and strategic deterrence, even in the context of escalating tensions.

With improved stealth capabilities and operational range, nuclear submarines are becoming increasingly important combat vehicles for deterrence purposes and carrying out extended underwater missions. Currently, several countries are investing significantly to develop or expand their nuclear submarine forces; at the same time, integrating advanced combat systems, such as long-range ballistic missiles, command and control systems using artificial intelligence (AI) and advanced sonar technology for this type of vehicle. The United States is the leading country in the race to develop nuclear submarines, with a huge defence budget. Accordingly, the US Navy is being modernised through investment in next-generation nuclear submarines, including the Virginia class and Columbia class. These submarines are integrated with advanced technology, such as: AI, cybersecurity and automation systems.

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Russia is also actively developing new-generation nuclear submarine classes, including attack submarines and ballistic missile submarines. Russia recently unveiled a new generation of nuclear submarines, the Arktur, to replace the Borei class. In addition, the Yasen-M class nuclear submarines, including the Perm launched in March 2025, have been upgraded to operate Zircon hypersonic missiles. These new-generation submarines will be equipped with advanced technology, powerful weapons and high stealth capabilities to enhance deterrence and protect Russia's national interests.

China is also investing heavily in nuclear submarine combat systems as part of its naval modernisation, through strengthening its submarine fleet for strategic deterrence and power projection; enhancing stealth capabilities, anti-submarine warfare and AI-controlled systems. At the same time, China has carried out programmes and projects to build Type 096 class nuclear-powered ballistic missile submarines, to prove itself as a key country in submarine warfare and ensure its naval dominance in the region.

Recognising the advantages of nuclear submarines, Australia has abandoned the diesel-electric submarine development programme with France to participate in the nuclear-powered submarine development cooperation programme among the US, UK and Australia, to address greater challenges in the region and create conditions for the country's naval forces to operate in the far sea area in the Indian Ocean - Pacific. In addition, countries are also stepping up investment in upgrading advanced weapons systems on diesel-electric submarines. Recently, the Russian Navy put into service the conventional diesel-electric attack submarine named Mozhaysk for the Pacific Fleet. The Mozhaysk is a third-generation large diesel-electric submarine, with a displacement of about 3,950 tons, capable of diving to a depth of more than 300 metres, operating continuously at sea for 45 days, equipped with a modern inertial navigation system, advanced automatic command and control communication systems, high-precision missile systems and high-explosive torpedoes. Germany is a key country in developing advanced diesel-electric submarine classes, especially the Type 212 and 214 classes, which focus on developing stealth technology, sonar systems and fuel cell propulsion systems to increase underwater capabilities. German defence companies are actively innovating submarine combat systems, which are of particular interest to NATO allies and other international customers.

Japan's diesel-electric submarines, including the newly developed Taigei-class and Soryu-class submarines, are being modernised with advanced combat systems, stealth technology, next-generation sonar, automation technology, and AI integration. In particular, Japan is the first country to install Li-ion batteries on diesel-electric submarines to enhance underwater diving capabilities. South Korea is also enhancing the capabilities of its KSS-III-class diesel-electric submarines, equipped with long-range missile systems, stealth technology, and advanced sonar. The country is also focusing on developing indigenous submarine combat systems, including AI-enabled solutions and automation systems, aiming to reduce dependence on foreign technology and boost the domestic defence industry to respond to regional security concerns.

Breakthrough in AI and stealth technology

Rapid advances in AI, automation, and stealth technology are creating breakthroughs in submarine development; allowing submarines to carry out complex missions with less risk and less chance of detection. Integrating AI into command, fire control, sonar and electronic warfare systems will help submarines increase their effectiveness and reduce the workload of the crew. AI technology is used to predict and counter underwater threats, control the execution of surface and underwater missions - marking significant advances in submarine capabilities. India has just announced the “Swarm of Unmanned Weapons Vessels and Unmanned Submarines” technology and officially equipped 30 unmanned submarines for the navy, marking a significant step forward in submarine combat capabilities and naval capabilities. With AI-enhanced onboard systems, it will transform underwater operations, enhancing sonar, fire control and communications capabilities. Another key trend that countries are focusing on is multi-domain combat capabilities and joint operations. Therefore, submarine combat systems in modern warfare will be built to integrate with multiple types of military vehicles, such as surface ships, aircraft and satellites. USS IDAHO (SSN 799) is the newest attack submarine of the US Navy, launched in August 2024, marking an important milestone in the construction process, when it is capable of coordinating operations in the air, on the water and in space. Such connectivity will enhance the role of submarines in naval operations, especially strategic deterrence and tactical operations.

Increasing the stealth capabilities of submarines through the application of soundproofing technology is also being invested in research and development by military powers. Advances in the development of new sound, sensor and noise-canceling technologies will enhance the advantage in submarine operations. Accordingly, noise-canceling technology for the engine compartment through the use of new soundproofing designs and additional coating materials for the hull will make submarines more difficult to be detected and achieve the so-called “Sound Advantage”. With this technology, new generation submarines can operate near enemy waters or coasts, carry out reconnaissance and attack missions without being detected and can detect all enemy movements and activities at a longer range. The sound advantage is also being exploited by countries focusing on the sensor aspect. Currently, the US Navy has begun to approach the fourth generation of underwater technology based on minimising the submarine's own appearance while being able to better detect enemy’s appearance. Emerging technologies also focus on passive, highly sensitive sound sensors that can detect enemy ships moving at longer ranges with greater fidelity.

Application of virtual reality technology and development of new engines

Submarine design based on virtual reality technology allows humans penetrate inside the submarine to make improvements in design, system layout, assess maintenance capabilities and access locations when needed. Users can also touch and feel the submarine, thereby making recommendations from an operational and exploitation perspective even before the first steel plate is cut to build the submarine. Requirements for disassembly and reassembly of the submarine during exploitation can also be met right at the design stage. Virtual reality environments combined with the real world create a mixed reality experience for submarine designers that will change the concept of submarine design in modern warfare.

In developing new submarine engines, the Chinese Navy has made great strides with the shaftless pump-jet engine - a revolutionary propulsion system. By eliminating the propeller shaft, reducing the number of moving parts, it will reduce the noise generated by the pump-jet engine, as well as save hull space. At the same time, China's latest submarines are being designed with an integrated electric propulsion system, which converts the entire output of the ship's engine into electricity that can be used to power the propeller or high-energy weapons. In addition, the integrated electric propulsion system has fewer moving parts, making the submarine quieter, making it harder to be detected. The pump-jet engine and the integrated electric propulsion system can significantly reduce the noise of nuclear submarines. This combination will be a significant step forward in China's naval power. China's nuclear submarines, when using these new technologies, will enhance their stealth capabilities as well as their survivability, and in turn, will increase the reliability of their second nuclear strike capabilities. These new submarine propulsion systems will not only provide power for future submarines, but also give Beijing the status of a true superpower submarine fleet.

With the continuous development of science and technology, military powers will continue to develop their submarine forces to maintain and consolidate their positions and gain superiority in modern warfare. However, this also makes the international community concerned about the risk of an arms race, threatening global security and stability.

Senior Colonel DANG DONG TIEN