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A popular conception is that international communications nowadays rely mainly upon satellites. This, though, is very far from being the case.
There are about 440 undersea cables stretching over a total of 885,000 kilometres. These cables carry some 95 per cent of the world's communications traffic, and in some cases, even electrical power. This network continues to expand, and it is emerging as a likely priority target in future conflict, particularly as the cables often lie the vicinity of strategic maritime chokepoints such as the Greenland/UK gap.
Underwater cables are vulnerable to operations by hostile players, including non-state actors. Such forces intend either to monitor classified traffic or to sever the cables in order to disrupt communications or power supply. The extreme depths at which many underwater cables are located demand the deployment of unmanned underwater vehicles (UUV).
Russia's special underwater missions ship Yantar has long been monitored while carrying out seabed operations in Middle Eastern waters and elsewhere. Yantar carries deep-diving manned submersibles as well as remotely operated underwater vehicles, both capable of operating on seabed infrastructure. The ship itself is also equipped with fixed and towed sonar systems for mapping the seabed.
Other important assets in Russia's seabed warfare inventory of nuclear-powered submarines include the huge Belgorod and the smaller specialised Losharik. The latter vessel is currently undergoing repairs following a major deadly fire in 2019.
According to reports, some of which are disputed, the Russians cut submarine internet cables leading into Crimea prior to annexing the territory in 2014.
China is increasingly dependent upon undersea cables to support its expanding and modernising economy, To mitigate the cables' vulnerability, Beijing is planning to establish two protected shore facilities for incoming cables as well as docking stations for UUVs along its pipelines and two specialist "underwater cable ships".
Beijing is also pursuing a policy of introducing a "Great Undersea Wall". This project, led by the China Shipbuilding Corporation, is intended to co-ordinate the operations of UUVs and seabed sensors to maintain underwater cables and to protect them against attack.
China is also increasingly proactive against the underwater cable networks of rival nations. Intelligence reports state that three Chinese survey vessels are active in the South China Sea, and sometimes carry out operations aimed at regional underwater communications networks. These ships have been identified as Ong Fang Hong, Hai Yang Di Zhi Ba Hao, and Shi Yuan 1.
A number of the "civilian" special mission ships of the US Navy's Military Sealift Command, such as the Pathfinder-class, are engaged in seabed surveillance, particularly in the South China Sea.
Furthermore, in order to safeguard its extensive underwater cable network, the US has activated its Forward Deployed Energy and Communications Outposts project. This is an array of fixed undersea docking stations that provides recharging, communications, and data transfer to extend UUV reach and endurance.
A vital component of future US Navy seabed operations will be the Orca-class Extra Large Unmanned Underwater Vehicle (XLUUV), five of which have been ordered from Boeing. The 16-metre Orca has a top speed of eight knots and a range of about 12,000 kilometres. It features a modular design, which is adaptable for a range of underwater missions.
Yantar was detected operating both off Ireland, and in the English Channel in 2021. The UK is particularly vulnerable to seabed warfare, as it depends upon an extensive network that includes both communications cables and interconnectors enabling the transfer of electrical power between UK and continental Europe.
The UK Royal Navy's ocean survey vessel Scott reportedly has some seabed warfare capability, and the RN is developing an XLUUV for such operations, with an experimental Manta XLUUV built by M-Subs currently undergoing trials.
A further project is the development of a specialised surface vessel, a Multi-Role Offshore Survey Ship (MROSS). It is unclear at present whether the MROSS requirement will be met by a dedicated naval or auxiliary vessel, or by a contracted civilian vessel.