Both the U.S. and Russia Are Stalking the World's Undersea Cables

The U.S. and Russian submarines are playing a game of cat and mouse above the undersea cables that carry the world's telecommunications and Internet data.
Marcia Wendorf

In July 2019, 14 Russian sailors onboard a submarine were killed in an accident. The top-secret submarine, believed to be the Losharik, was attempting to dock with a larger submarine when an explosion occurred in her battery compartment. Rather than evacuating, the 14 sailors closed a hatch and fought the resulting fire.

The Loshiarik can operate at depths other submarines cannot reach, and Western intelligence agencies have speculated that her mission was to tap information flowing through undersea cables. These cables form the backbone of worldwide communications.

The cables carry 95 percent of daily worldwide communications, plus they carry financial transactions worth over $10 trillion a day. Any disruption would cause a catastrophic cut in the flow of capital.

Where these undersea cables come ashore are called "landing areas," and the U.S. Department of Homeland Security lists these landing areas at the top of their list of "critical infrastructure."

Undersea Telegraph Cables

The first undersea transcontinental telegraph cable was completed in the summer of 1858. It ran under the Atlantic ocean from Newfoundland to Ireland, and it carried the first official telegraph message sent by Queen Victoria to U.S. President James Buchanan. That 509-letter message took 17 hours and 40 minutes to arrive.

Between the years 1858 and 1911, Britain's vast colonial empire required communication, and entrepreneurs in Britain financed the building, laying and maintenance of the first undersea telegraph cables.

Telegraph communication meant that ships could be directed to pick up cargo, governors of the various colonies could be in contact with London, and Britain could coordinate her military units.

During the 1860s and 1870s, Britain expanded her undersea cable telegraph network eastward into the Mediterranean Sea and the Indian Ocean. In 1870, a cable linking Bombay, India to London was completed by a consortium of four cable companies, and in 1872, these four companies combined to form the Eastern Telegraph Company.

Eastern Telegraph system in 1901
Eastern Telegraph system in 1901. Source: A.B.C. Telegraphic Code/Wikimedia Commons

A spin-off company, the Eastern Extension China and Australasia Telegraph Company, was formed, and in 1876, it linked Australia, Bombay, Singapore, and China.

In the Pacific Ocean, the U.S. linked to Hawaii in 1902, and that same year, Canada, Australia, New Zealand, and Fiji were connected. Japan came on board in 1906.

Undersea Telephone Cables

It wasn't until 1955 that the first transatlantic telephone cable, TAT-1 was laid between Oban, Scotland, and Clarenville, Newfoundland. It was inaugurated on September 25, 1956, and carried 36 telephone channels.

Undersea Fiber-Optic Cables

The first fiber-optic cables were developed in the 1980s, and the first fiber-optic transatlantic telephone cable was TAT-8, which went into operation in 1988. Today's fiber-optic cables have their fibers arranged in a self-healing ring to increase redundancy, and their submarine sections follow different paths along the ocean floor. Some systems have dual landing points where they come onshore.

Cross section of a fiber-optic cable
Cross-section of a fiber-optic cable. Source: Oona Räisänen/Wikimedia Commons

Today, 99 percent of the data crossing the oceans is carried by undersea cables. As of 2012, data was flowing error-free at 100 Gbps across Atlantic Ocean routes of up to 6,000 km (3,700 mi). That meant that a typical cable was capable of moving tens of terabits of data per second, with the fastest transatlantic connections taking less than 60 milliseconds (1/1,000 of a second).

2007 map of undersea cables
2007 map of undersea cables. Source: Rarelibra/Wikimedia Commons

Undersea Cables and National Security

Britain's very first action after declaring war in World War I was to have the cable ship Alert cut the five undersea cables that linked Germany to France, Spain, the Azores, and North America.

This forced the Germans to communicate by wireless, which meant that the cryptoanalysis section of the British Admiralty during WWI, known as Room 40, could listen in.


Today, the Pentagon is worried that ships like the Losharik appear to be accessing undersea cables at much greater depths, where the cables are harder to monitor and repair.

They are particularly worried that the Russians can tap into these cables, something that the American agencies have been able to do for a long time. The U.S. has "Network Security Agreements" with the cable operators that allow it to conduct surveillance on a majority of the world’s voice and internet traffic.

The U.S. ensures the compliance of the cable operators by allowing the Federal Communications Commission (FCC) to hold up approvals for new cable licenses. The extent of the National Security Agency’s (NSA) access to fiber-optic cables is classified.

Because ships need to be made aware of cable locations, maps of submarine cables are widely available. This poses security issues for the various nations. Websites such as TeleGeography display maps and lists of the almost 350 cables spanning over 550,000 miles of ocean.

In recent years, there has been increased Russian naval activity along known cable corridors. A 2015 New York Times article described how American spy satellites, ships, and planes monitored the Russian spy ship Yantar as she followed a cable off the East Coast of the U.S.

The U.S. has also laid secret cables that are used for military operations, and that aren't marked on available maps. It's possible that Russian ships, such as the Losharik, are searching for these cables.

Today, Australia considers its submarine cable system to be "vital to the national economy," and the Australian Communications and Media Authority (ACMA) has created zones to protect cables to restrict activities that could damage cables.

Cable Repair

Cables can be broken by ship's anchors, fishing trawlers, earthquakes, currents, and even shark bites. After 1980, cables were buried, but that didn't stop significant breaks from happening.

In 1929, the Newfoundland earthquake caused a massive undersea mudslide that broke several trans-Atlantic cables. In July 2005, a cable providing Pakistan's major communications went down, disrupting approximately 10 million Internet users.

In 2006, the Hengchun earthquake rendered cables between Taiwan and Philippines inoperable, and in 2008, three separate incidents caused cables to be damaged in the Mediterranean Sea and the Middle East.

In 2011, the Tohoku earthquake damaged cables leading to Japan, and in August 2017, an undersea cable near Jeddah, Saudi Arabia disrupted internet service again to Pakistan.

To repair cable, repair ships either bring the entire cable to the surface or else they cut the cable and bring up only the damaged portion. Then, a new section is spliced in.

Undersea cable laying ship
Undersea cable-laying ship. Source: David Monniaux/Wikimedia Commons


Today, Antarctica remains the only continent not connected by a submarine telecommunications cable. Fiber-optic cable there would have to withstand temperatures of -80 degrees C (-112 degrees F) and the strain of flowing sea ice.

Add Interesting Engineering to your Google News feed.
Add Interesting Engineering to your Google News feed.
message circleSHOW COMMENT (1)chevron
Job Board