Submarine Detection and the Future of the U.S. Fleet (2024)

By: Ryan Neuhard, Columnist

Photo by: Navy Times

Improvements in submarine detection capabilities are eroding the stealth that US submarines rely upon for survival.[[i]] Advances in instrument sensitivity, data processing, robotics, seabed infrastructure, and communications technology underpin these improvements.[[ii]] As these capabilities begin to expose US submarines to anti-submarine forces, the United States may need to reconsider how it designs, equips, and deploys its submarine fleet.

Detection Capabilities

Advances in instrument sensitivity and data processing are making it possible for anti-submarine forces to pick out increasingly subtle signatures from background noise. Key instruments include passive sonars, active sonars, synthetic aperture radars, and magnetic anomaly sensors. [[iii]] These sensors detect submarine noise emissions, hull material, surface wakes, and magnetic field disturbances. More powerful computers and data processing algorithms capitalize on these sensors’ increasingly granular data by refining data and identifying obscure patterns. [[iv]]

The development of robotics, seabed infrastructure, and underwater communications are now providing opportunities to integrate these capabilities into large detection networks. These networks can incorporate mobile unmanned underwater vehicles, fixed seabed and buoy sensors, and potentially independent commercial infrastructure, like sensors monitoring fish stocks.[[v]] Real-time underwater communication systems can then exchange information between these sensors to pinpoint submarines and alert anti-submarine forces.[[vi]]

Among our competitors, China may be emerging as the pacing challenger. After decades of emphasizing land warfare, China is now attempting to develop its naval forces — and this includes anti-submarine capabilities.[[vii]] Much of China’s recent activity has involved building up its fleet of anti-submarine ships and aircraft.[[viii]] Perhaps more importantly, China has also begun rolling out the unmanned systems and network capabilities needed for next generation submarine detection.[[ix]] While it is difficult to track the progress of military research and development efforts, there are periodic reports of sensor and computing breakthroughs that could be applied to submarine detection, which suggests China is making progress.[[x]] This growing interest in anti-submarine capabilities aligns with the Chinese government’s broader interest in expanding China’s ability to project maritime power and pursue objectives like the Belt and Road Initiative, the South China Sea claims, and Taiwan reunification.[[xi]] Given this strategic outlook, we can expect China to continue developing its anti-submarine capabilities for the foreseeable future.

Effect on Future Operations

The United States has several options for responding to the detection problem. First, the United States can develop future submarines designs that further reduce sound emissions, sound and radio wave signatures, and magnetic field disturbances. Second, the United States can outfit submarines with additional defensive countermeasures to make them more resilient to attack when exposed. Third, the United States can shift submarines from a frontline role to a standoff role.

Current submarine designs emphasize sound dampening and hydrodynamics. These designs help reduce the sound emissions and surface disturbances that alert passive sonars and active radars. Developing even quieter propulsion and engine designs can help submarines stay ahead of improving passive sonar systems, while drag-reducing designs can help submarines reduce wake and evade active radar. [[xii]] However, these design priorities do not address the submarine’s visibility to active sonar or magnetic anomaly sensors. To defeat active sonar, submarines can experiment with hull shapes and coatings that improve the absorption or deflection of sound waves. [[xiii]] To defeat magnetic anomaly sensors, future designs can reduce the amount of magnetic materials used in a submarine’s construction or attempt to use magnetic cloaking techniques to reduce a submarine’s signature. [[xiv]]

The United States can also anticipate an increase in detection and outfit submarines with better means to defend themselves. Countermeasures can include improved jammers, decoys, and interceptors, as well as unmanned support vehicles and counterattack capabilities. Improved jammers and decoys can disable or divert anti-submarine weapons’ homing systems, while interceptors can destroy the weapons before they reach the submarine. [[xv]] Unmanned underwater vehicles can be used to form a defensive perimeter around the submarine to detect and neutralize approaching threats before they come into range of the submarine, much like an aircraft carrier’s escort ships. The submarine can also expand their torpedo and missile armaments, at the expense of long-range land-attack weapons, in order to better retaliate against air, surface, and subsurface threats.

US submarines could also shift from frontline combat and surveillance roles to backfield coordination and host roles. A recent report from the Center for Strategic and Budgetary Assessment outlined what this transition might look like and drew parallels to the role of today’s aircraft carriers. [[xvi]] In the future, submarines could avoid operating in high-risk waters accessible to enemy forces and instead serve as a mothership for smaller, more expendable unmanned underwater vehicles that could conduct the high-risk, frontline missions. The submarine could also serve as a communication hub for processing and distributing information gathered by the unmanned vehicles’ sensors. The Navy’s recent experiments with submarine-launched unmanned vehicles and the Navy’s unmanned vehicle-related requirements for future attack submarines suggest that the United States may already be moving toward this model of operations. [[xvii]]

Conclusion