The United States is conducting the biggest upgrade of its secret underwater listening systems since the Cold War, amid concerns about the rising threat of the Chinese navy.
Defence analysts in Washington are concerned the country is looking to expand naval operations beyond its own waters, posing a greater threat to Taiwan and the US in the Indo-Pacific region.
In October, the Pentagon will publish its annual assessment of China’s defence capability, which has assessed the build-up of the country’s military and its threat to the US every year since 2000.
As part of its latest China strategy, the US has stepped up the Integrated Undersea Surveillance System (IUSS), its underwater detection programme, first launched to hunt Soviet submarines during the Cold War.
The IUSS is deploying new underwater drones, similar to those ordered by the UK’s Ministry of Defence, to monitor submarine activity and protect the US’s undersea cable network.
Similar technology has been sold to Australia in the hope it can counter Chinese influence in the South Pacific.
The IUSS’s stations on the east and west coasts of America provide intelligence on submarine and underwater activity in the Pacific and Atlantic oceans, using a combination of seabed hydrophones, aircraft, submarines and surface vessels.
One of the bases, in Dam Neck, Virginia, is home to the largest group of Royal Navy and RAF personnel in the United States, and is thought to be the station that detected the collapse of the Titan submersible off the coast of Newfoundland in June.
The Pentagon has also announced a new “Replicator” programme of autonomous drones that it says would “overcome [China’s] biggest advantage, which is mass”.
US military sources said that the multi-billion dollar upgrades are due in part to concerns about the Chinese navy’s recent acquisitions.
China operates the largest navy in the world, with more than 340 vessels, and is developing a range of new ships and upgrades to its existing fleet.
China’s new technology includes a third aircraft carrier for its fleet, which is currently undergoing sea trials ahead of a launch next year, and upgraded frigates with quieter engines and longer range.
In addition to new air bases, largely built on uninhabited islands, the Pentagon now believes China is operating a continuous at-sea nuclear submarine presence, similar to the Trident programme operated by the UK.
In July, the Chinese navy tested a new, longer-range engine for its J-20 “Mighty Dragon” fighter jets, which have put the planes in range of US bases in South Korea and Japan.
Advanced version of its biggest frigate
In August, China launched a more advanced version of its biggest frigate which will travel faster, go further, and is harder to detect, making it better at anti-submarine tasks.
At a helicopter expo in Xinjiang last week, China showcased a new helicopter engine that is thought to be a building block for an upgraded fleet of medium-range naval helicopters.
Xi Jinping, the Chinese president, has announced he will use force to reunify Taiwan and China if necessary, warning Western countries not to “interfere” in its sphere of influence in the East China Sea.
Analysts believe the naval upgrades may be an attempt to construct an “anti-access/area denial” strategy, which would use a combination of planes, submarines, surface vessels and missiles to prevent the US from intervening to prevent an invasion of Taiwan.
The concerns come as Joe Biden, the US president, attempts to pass his proposed 2024 defence budget, which has been held up by Republicans over its cost and concern about “woke” policies at the Pentagon.
The White House said the plans have a “laser focus on China” and include funding for nine new ships, including four submarines.
In March, Lloyd Austin, the US defence secretary, described China as the US’s “only competitor, with both the intent and increasingly the capacity to reshape the international system to suit its autocratic preferences”.
Kathleen Hicks, his deputy, said in August that China’s “slow and lumbering” Cold War era military now had the capacity to “blunt the operational advantages we’ve enjoyed for decades”.