Tracking US subs may be formidable, but China is trying to change the game

In the race for dominance in deep sea military capability, the United States remains the "unchallenged" leader with its fleet of dozens of nuclear-powered ballistic missile submarines patrolling the globe virtually undetected. But China may soon challenge that and change the game at sea.

The American vessel USS West Virginia has been described as one of the "stealthiest" vessels in the US Navy squadron and can stay underwater for as long as 70 days.

Sightings are rare for the 33-year-old vessel, which is armed with Trident ballistic missiles. Its public appearance is often interpreted as carrying a message, like when it surfaced in an undisclosed location in international waters in the Arabian Sea on October 2022, to welcome US military commander for the Middle East, General Erik Kurilla.

In July, the nuclear-capable submarine, USS Kentucky, docked in South Korea for the first time in 40 years. South Korea's President Yoon Suk Yeol even boarded the vessel in Busan, sending a strong warning to rival North Korea.

Another submarine, the 7,800-tonne USS Mississippi is equipped to carry torpedoes and Tomahawk missiles. It is described as having the capacity "to insert special operations forces into a multitude of environments and battlefield scenarios".

In November, USS Mississippi made a port visit to Perth in Australia and conducted joint training exercises with the Royal Australian Navy.

Australia itself is reportedly on track to acquiring at least three submarines similar to USS Mississippi in the early 2030s, raising alarms in Bejing, which criticised the deal as a manifestation of “Cold War mentality”, which it said is making the world less safe.

In recent months, the US also commissioned another vessel, the USS Delaware with US President Joe Biden and First Lady Jill Biden present. The nuclear-powered submarine is longer than a football field and can travel at a depth of at least 800 feet at a maximum speed of about 30mph.

So far, there are at least 49 fast-attack submarines in the US Navy fleet that are specifically capable of attacking and sinking other submarines, surface combatants and merchant vessels.

With US naval superiority in terms of actual firepower and technology, detecting, tracking and potentially hitting submarines are a challenge for other countries, as the tasks require equally sophisticated technology and training.

Tensions in recent weeks and months in the resource-rich South China Sea have highlighted the rivalry between Washington DC and Beijing, while also putting a spotlight on both nations' naval firepower.

Picking up electromagnetic signals

Submarines must operate quietly in order to evade enemy sensors, because water is a highly efficient conductor of sound, according to the Nuclear Threat Initiative (NTI) website.

The main source of noise from a submarine is said to be coming from its propulsion system, thus, the design and quality of the propeller blades matter greatly in ensuring the survivability of a country’s sea-based nuclear deterrent, it added.

For years, the US as well as China, have built networks of hydro-acoustic sensors, which use sonar technology to detect submarines navigating close to their coastal borders and strategic military locations.

That technology, however, also depends on the level of noise submarines produce while underwater. In the case of US submarines, they might be harder to observe.

In contrast, China’s Jin-class nuclear-powered ballistic missile submarines reportedly produce more sound, pointing to one possible reason why Chinese submarines rarely stray from coastal to deeper waters, NTI explained.

Other monitoring and submarine detection technology have been employed in the past, including the magnetic anomaly detectors (MAD) employed by anti-submarine warfare (ASW) units of advanced navies around the world.

MAD specifically detects tiny disturbances to Earth’s magnetic field caused by metallic submarine hulls.

Radar and high-resolution satellite imagery have also helped detect submarines above water and analyse the size and composition of countries’ submarine fleets and submarine constructions among others.

But in a possible breakthrough, Chinese researchers have discovered a new way of detecting submarines using available devices to pick up extremely low-frequency electromagnetic signals produced by the speeding submarines, allowing them to potentially locate the actual movements of those underwater vessels.

That gives the world's second-largest economy a new device in its toolbox challenging American dominance at sea.

Citing a new study published earlier this month, the South China Morning Post reported that Chinese scientists also found that the almost imperceptible bubbles produced by the passing submarines could also give away the position of those vessels.

More research is still needed to advance the detection process, scientists say, but findings may be substantive enough for the paper to be allowed by Beijing to get published.

Submarine-hunter drones

As part of its military effort to continue to challenge American dominance at sea, China unveiled in 2022 advanced unmanned drones known as "submarine hunters".

According to the China Academy of Aerospace Aerodynamics in Beijing, the new CH-series drones can handle "complicated marine situations and environments".

The new drones are also equipped with electronic and optical reconnaissance apparatus and wide-field detection radars, capable of locating, monitoring and engaging hostile targets over a vast sea area, Shi Wen, the designer of the drone, was quoted as saying by the China Daily website.

According to Shi, the CH-5 drone has a maximum speed of 290 kilometres per hour but usually flies at cruising speeds ranging from 180 to 220 km/h, allowing it to be deployed within a short period and possibly reach targets quicker.

The new drones have a maximum takeoff weight of 3.3 metric tonnes per drone and can carry up to 480 kilograms of equipment and weapons.

According to the report, the aircraft is also capable of staying in the air for up to 35 hours, allowing for extended operation.

Wu Peixin, an aviation industry observer in Beijing, was quoted by China Daily as saying that the "biggest advantages" of such drones are that they can stay much longer over the target zone, are much cheaper to buy, operate and maintain, "and that several drones can be networked to increase the odds of finding hostile submarines."

With limited use, however, it still remains to be seen how effective the Chinese drones are against the US submarines. What is clear is that Beijing is actively seeking ways to equalise the playing field and change the game.