Undersea Telecommunication Cables: Technology Overview and Issues for Congress

Undersea Telecommunication Cables: Technology Overview and Issues for Congress

Undersea Telecommunication Cables:
September 13, 2022
Technology Overview and Issues for Congress
Jill C. Gallagher
Undersea telecommunication cables enable consumers, businesses, and governments, including
Analyst in
the military, to communicate with each other and to access the internet. Private and state-owned
Telecommunications
telecommunication and technology companies operate about 486 undersea telecommunication
Policy
cables, which connect every continent except Antarctica. These privately owned cables carry

about 99% of transoceanic digital communications (e.g., voice, data, internet), including trillions
of daily international financial transactions, and serve as the backbone for the global internet.

Recent damage and threats to commercial undersea telecommunication cables have raised concerns among U.S. officials and
experts over the security of commercial undersea telecommunication cables. In January 15, 2022, a volcanic eruption and
earthquake in Tonga severed its only connection to the internet. Repair crews restored service to the main island within
several weeks; however, the cable connecting Tonga’s 170 outer islands to the main island and to each other is still under
repair, leaving people and businesses in those areas without service. The outage of its sole cable disrupted Tonga’s
communications, recovery efforts, and financial markets, including remittances from abroad on which many families depend.
Russia’s invasion of Ukraine has also increased concern about the security of commercial undersea telecommunication cables
among some North Atlantic Treaty Organization (NATO) nation leaders, given previous reports of Russian capabilities to cut
or tap undersea cables and its activities near NATO nations’ undersea infrastructure. The U.S. Department of Justice raised
issues related to commercial undersea cables connecting the United States to China, citing increased potential for the Chinese
government to access undersea cable systems to obtain personal information, data, and communications. Finally, a
cyberattack on a commercial undersea telecommunication cable connecting Hawaii and the Pacific region has raised
awareness and concern among U.S. officials on the cybersecurity of commercial undersea telecommunication cables.
The U.S. government has studied security of commercial undersea telecommunication cables in the past. A 2017 report
sponsored by the Office of the Director of National Intelligence (ODNI) found that the majority of disruptions are caused by
human activity (e.g., fishing, anchoring, dredging) and natural disasters. The ODNI report found there are few disruptions of
cables in proportion to their heavy presence and use. Automated detection systems, increased redundancy of routes, and a
network of repair ships has led to a high degree of resiliency in the global undersea cable network. However, the ODNI report
asserted that risks are increasing, due to the heavy reliance on undersea cables, increasing volume of data transmitted through
undersea cables, and technological improvements to cable systems that have created new vulnerabilities. The Communication
Security, Reliability and Interoperability Council (CSRIC)—a federal advisory committee to the Federal Communications
Commission (FCC)—issued a series of reports identifying risks to cables and recommendations for strengthening the security
and resiliency of commercial undersea telecommunication cables. The CSRIC identified a need for a lead agency to improve
coordination among U.S. government agencies involved in reviewing cable landing applications; increase coordination
between the U.S. government and private sector owners to establish and promote protection standards (e.g., protection zones,
spatial separation standards); and promote participation in international organizations aimed at protecting undersea
telecommunication cables.
The U.S. government has acted to protect undersea telecommunication cables and the U.S. telecommunication network. It
has strengthened processes for reviewing foreign ownership interest of cables landing in the United States; restricted the use
of untrusted equipment in undersea cable systems; encouraged investment in trusted equipment in the United States and
abroad; established an outage reporting system for undersea cables; and expanded its cable repair fleet. Some have called for
a more coordinated approach to securing undersea cables such as appointing a lead agency to oversee cable security or
establishing a public-private initiative to enhance cable security. On the one hand, these are private assets, maintained by
their owners, with few disruptions reported. On the other hand, given the heavy reliance on commercial undersea cables for
consumer, financial, government, and some military communications, and given the increasing threats from human activity,
natural disasters, and bad actors, Congress may increase U.S. government oversight and involvement in ensuring security of
commercial undersea telecommunication cables.
This report discusses the technology of undersea telecommunication cables, threats to cables, U.S. government actions to
protect cables, and issues for congressional consideration.
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Contents
Introduction ..................................................................................................................................... 1
Undersea Telecommunication Cable Systems ................................................................................. 2
Dry Plant ................................................................................................................................... 5
Cable Landing Station......................................................................................................... 5
Beach Manhole ................................................................................................................... 6
Wet Plant ................................................................................................................................... 6
Fiber-Optic Cable ................................................................................................................ 6
Recent Technical Developments ..................................................................................................... 8
Threats to Undersea Telecommunication Cables ............................................................................ 9
Unintentional Damage to Cables............................................................................................... 9
Human Activities .............................................................................................................. 10
Natural Disasters ............................................................................................................... 10
Intentional Damage to Undersea Telecommunication Cables .................................................. 11
Repairing Damaged Undersea Telecommunications Cables ................................................... 12
Cyberattacks ............................................................................................................................ 13
U.S. Actions to Protect Cables ...................................................................................................... 13
Foreign Ownership Review ..................................................................................................... 14
Restrict Use of Untrusted Equipment ...................................................................................... 15
Facilitate Investment in Trusted Equipment ............................................................................ 16
Enhance Cable Security Review ............................................................................................. 17
Monitor Cable Outages ........................................................................................................... 18
Identify Policies and Standards to Protect Cables ................................................................... 18
Invest in Cable Repair Vessels ................................................................................................ 18
Issues for Congress ........................................................................................................................ 19
Role of U.S. Government in Protection of Cables .................................................................. 19
Connections with Adversarial Nations .................................................................................... 20
Restrictions on Technologies or Technology Firms ................................................................ 21
Strengthening Security Requirements ..................................................................................... 21
Addressing the Risk of Damage Through Commercial Activity............................................. 21
Conclusion ..................................................................................................................................... 21

Figures
Figure 1. Map of Commercial Undersea Telecommunications Cables ........................................... 4
Figure 2. Undersea Telecommunication Cable System ................................................................... 5
Figure 3. Undersea Fiber-Optic Cable Cross-Section ..................................................................... 7
Figure 4. Cause of Undersea Telecommunication Cable Faults (1959 to 2021) ........................... 10

Contacts
Author Information ........................................................................................................................ 22

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Undersea Telecommunication Cables: Technology Overview and Issues for Congress

Introduction
Telecommunications providers have used undersea cables (also known as submarine or subsea
cables) for long-distance communications for more than 170 years. The English Channel
Submarine Telegraph Company laid the first undersea cable in 1850 between England and
France, to enable international communications over telegraph.
The first successful transatlantic telegraph message carried by undersea cable was transmitted in
1858, the first transatlantic telephone cable entered operation in 1956, and the first transatlantic
fiber-optic cable was laid in 1988.1 The fiber-optic cable, called the TAT-8, had the capacity to
carry 40,000 telephone connections simultaneously, four times the capacity of previous cables.2
One telecommunication market research and consulting firm that maps undersea cables, estimates
that, as of April 2022, there are 486 commercial undersea telecommunication cable systems and
1,306 landing stations (i.e., the point where the undersea cable makes landfall) currently active or
under construction.3 The cables connect every continent except Antarctica,4 and serve as the
backbone for the global internet.5 Industry experts estimate that the undersea telecommunication
cable network carries about 95% of intercontinental global internet traffic,6 and 99% of
transoceanic digital communications (e.g., voice, data, internet),7 including trillions in
international financial transactions daily.8
With the proliferation of mobile phones and other devices that connect wirelessly to
telecommunication networks, and the global expansion of those networks, demand for mobile
data is increasing. One industry report estimates that in 2020, amid the COVID-19 pandemic, the
global market for mobile data traffic was 47.6 million terabytes per month; the report projects it
to reach 220.8 million terabytes per month by 2026, growing at a compound annual growth rate
of 28% over the analysis period.9 The growth is driven in large part by video use, as well as the

1 Mischa Schwartz and Jeremiah Hayes, “A History of Transatlantic Cables,” IEEE Communications Magazine, vol.
46, no. 9 (September 12, 2008), pp. 42-48, https://ieeexplore.ieee.org/document/4623705; Gerard Fouchard, “Historical
Overview of Submarine Communication Systems,” in Undersea Fiber Communication Systems, ed. Jose Chesnoy, 2nd
ed. (London: Academic Press, 2016).
2 CBR Staff Writer, “Fibre Optic TAT-8 Cable Goes into Service across the Atlantic,” Tech Monitor, December 15,
1988, https://techmonitor.ai/techonology/fibre_optic_tat_8_cable_goes_into_service_across_the_atlantic.
3 Jayne Miller, “Two New Maps, Lots of New Cables,” TeleGeography (blog), April 4, 2022,
https://blog.telegeography.com/two-new-maps-lots-of-new-cables.
4 TeleGeography, “Submarine Cable Frequently Asked Questions: Submarine Cable 101,”
https://www2.telegeography.com/submarine-cable-faqs-frequently-asked-questions.
5 Brian E. Carpenter, Network Geeks: How They Built the Internet (London: Springer Science & Business Media,
2013), p. 80.
6 Justin Sherman, Cyber Defense Across the Ocean Floor: The Geopolitics of Submarine Cable Security, Atlantic
Council Scowcroft Center for Strategy and Security, September 13, 2021, https://www.atlanticcouncil.org/in-depth-
research-reports/report/cyber-defense-across-the-ocean-floor-the-geopolitics-of-submarine-cable-security/.
7 Christian Bueger and Tobias Liebetrau, “Protecting Hidden Infrastructure: The Security Politics of the Global
Submarine Data Cable Network,” Contemporary Security Policy, vol. 42, no. 3 (2021), pp. 391-413,
https://www.tandfonline.com/doi/full/10.1080/13523260.2021.1907129.
8 The International Cable Protection Committee, Submarine Cables and BBNJ (Biodiversity in areas Beyond National
Jurisdiction), 2016, p. 1, https://www.un.org/depts/los/biodiversity/prepcom_files/ICC_Submarine_Cables_&
_BBNJ_August_2016.pdf; see also Maritime Awareness Project, “Factsheet: Submarine Cables,” https://map.nbr.org/
2018/07/submarine-cables/.
9 Global Industry Analysts, Inc., “New Analysis from Global Industry Analysts Reveals Steady Growth for Mobile
Data Traffic, with the Market to Reach 220.8 Million Terabytes per Month Worldwide by 2026,” PR Newswire,
December 8, 2021, https://www.prnewswire.com/news-releases/new-analysis-from-global-industry-analysts-reveals-
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expansion of data center and cloud services—especially intensive data communications for large-
scale distributed data storage, management, and process—made available to companies by cloud
computing service providers (e.g., Amazon, Microsoft, Google). Increase in demand for these
services has driven demand for additional cables with increased capacity.10
Recently, some national security observers have called attention to the importance of commercial
undersea telecommunication cables, and recommended greater U.S. government involvement in
cable planning to protect cables from unintentional and intentional damage, and to prevent
foreign adversaries from accessing communications and data transmitted through cables.11 The
recommendations overlap those made in a 2017 report sponsored by the Office of the Director of
National Intelligence (ODNI)12 and by the advisory committee to the Federal Communications
Commission (FCC) in a series of reports on undersea cable security and resiliency, issued from
2014 through 2016.13 Recommendations include physical protection policies, public-private
cooperation on cable security, education, and international engagement to protect commercial
undersea telecommunication cables from damage and espionage. With the emergence of fifth-
generation (5G) telecommunications technologies, Congress has shown an interest in protecting
U.S. and global terrestrial (land-based) telecommunication networks.14 Given the importance of
commercial undersea cables for carrying 5G and internet data traffic, Congress may also focus on
the security of undersea cables and the data they carry, and the role of the U.S. government in
protecting these privately-held assets.
This report provides an overview of undersea telecommunication cable technologies, threats to
undersea telecommunication cables (unintentional and deliberate damage), and U.S. government
actions to protect cables. The report concludes with issues for congressional consideration,
including additional federal policies and measures to protect cables such as restricting landing
cables in the territory of nations deemed to be adversaries; restricting the use of equipment from
firms in nations deemed to be adversaries; and policies to mitigate threats to and strengthen the
security and resiliency of commercial undersea telecommunication cables.
Undersea Telecommunication Cable Systems
When people communicate using wired or wireless digital devices, the information they send
often traverses multiple interconnected telecommunication service networks before reaching the
intended recipient. Telecommunication and internet service providers use high-capacity terrestrial
(land-based) networks to carry communications within contiguous landmasses. However, to

steady-growth-for-automotive-ethernet-with-the-market-to-reach-4-9-billion-worldwide-by-2026—301576778.html.
10 Stephanie Wong, “Google’s Subsea Fiber Optics, Explained,” Google (blog), April 6, 2022,
https://cloud.google.com/blog/topics/developers-practitioners/googles-subsea-fiber-optics-explained (Stating “Cloud is
a big growth driver of Google’s network demand, with Gartner predicting the world’s cloud spending to increase to
$917B by 2025.”)
11 Justin Sherman, Cyber Defense Across the Ocean Floor: The Geopolitics of Submarine Cable Security, Atlantic
Council Scowcroft Center for Strategy and Security, September 13, 2021; see also Jonathan E. Hillman, Securing the
Subsea Network, A Primer for Policymakers, Center for Strategic and International Studies, A Report of the CSIS
Reconnecting Asia Project, March 2021, https://www.csis.org/analysis/securing-subsea-network-primer-policymakers.
12 ODNI, Threats to Undersea Cable Communications (ODNI Report), September 28, 2017, https://www.dni.gov/files/
PE/Documents/1—2017-AEP-Threats-to-Undersea-Cable-Communications.pdf.
13 The reports are available at FCC, “Communications Security, Reliability, and Interoperability Council (CSRIC),
Reports,” https://www.fcc.gov/CSRICReports.
14 For further details, see CRS Report R47012, U.S. Restrictions on Huawei Technologies: National Security, Foreign
Policy, and Economic Interests, by Jill C. Gallagher.
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transmit communications between landmasses separated by large expanses of water,
telecommunication and internet service providers rely on undersea telecommunication cables.
Providers transmit voice and data communications through their terrestrial networks in the
originating geography through an undersea cable to a terrestrial network in the terminating
geography, which carries them to the intended recipients.15
Telecommunication companies (e.g., AT&T, Verizon, Deutsche Telekom, China Mobile), own and
operate most undersea cables.16 One company or a consortium of companies may own a single
commercial undersea telecommunication cable. In the late 1990s, consortia of companies and
investors built undersea cables and sold the capacity to carriers. According to a report from one
policy think tank, single-owner entities own around 65% of the undersea telecommunication
cables, while consortia own 33%.17 Starting around 2015, technology companies, such as
Google,18 Facebook, and Amazon, began investing in and building their own undersea cables, as
sole owners or as parts of a consortium, to meet increasing demands.19
In the United States, as well as in many other nations, repair and maintenance of commercial
undersea telecommunication cables is primarily a private sector responsibility. Cable owners may
develop agreements between themselves and with other infrastructure owners (e.g., offshore
power transmission cable and pipeline owners). These private agreements could define the
placement of the respective infrastructures; crossing notification procedures, where owners agree
to install cables at minimum distances apart in locations where a cable may cross an existing
undersea telecommunication cable or other infrastructure; and access agreements for maintenance
and repair, to avoid harm to cables.
Figure 1 shows the geographic distribution of undersea telecommunication cables in June 2022.20

15 Bryan Clark, “Undersea Cables and the Future of Submarine Competition,” Bulletin of the Atomic Scientists, vol. 72,
no. 4 (2016), p. 234, https://www.tandfonline.com/doi/pdf/10.1080/00963402.2016.1195636.
16 TeleGeography, “Submarine Cable Frequently Asked Questions: Submarine Cable 101,”
https://www2.telegeography.com/submarine-cable-faqs-frequently-asked-questions.
17 Justin Sherman, Cyber Defense Across the Ocean Floor: The Geopolitics of Submarine Cable Security, Atlantic
Council Scowcroft Center for Strategy and Security, September 13, 2021. (Note: Total ownership does not add up to
100% because ownership of some cables was not provided to or coded by TeleGeography, the author’s data source.)
18 In 2015, Google formed a parent company named Alphabet; Google is the largest wholly owned subsidiary of
Alphabet.
19 Alan Mauldin, “A Complete List of Content Providers’ Submarine Cable Holdings,” TeleGeography Blog,
November 9, 2017 (updated 2020), https://blog.telegeography.com/telegeographys-content-providers-submarine-cable-
holdings-list. There are many types of technology firms such as internet service providers (e.g., AT&T, Comcast),
content providers or over-the-top providers (e.g., Netflix, Hulu), hyperscalers or web-scale companies (e.g., Google,
Apple, Facebook, Microsoft, and Amazon), cloud service providers (e.g., Amazon, Microsoft, Google, and IBM), etc.
TeleGeography uses the term “content providers” but notes that the top four investors—Google, Facebook, Amazon,
and Microsoft—are hyperscalers.
20 The map shows commercial undersea telecommunication cables, and does not include many government-owned
cables. For example, the U.S. Navy operates about 40,000 miles of undersea cables. For awareness, there are other
types of cables, such as undersea power cables, which provide electric power transmission service across regions.
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Figure 1. Map of Commercial Undersea Telecommunications Cables

Source: TeleGeography, Submarine Cable Map, 2022, https://www.submarinecablemap.com/.
Note: Geographic distribution of commercial undersea telecommunication cables as of June 15, 2022. Colors
are used in the figure to visually differentiate undersea telecommunication cables in close proximity to one
another. Colors may repeat in different geographic areas. The hol ow circles signify cable landing stations. This
map shows both domestic and international undersea telecommunication cables. Domestic undersea
telecommunication cables lay point to point within a country to improve connectivity between regions within a
country, and provide connectivity to the global internet. Some domestic cables cross into international waters
when connecting two domestic points. International cables connect two or more countries; these enable
connection between the countries and to the global internet. This map shows commercial cables and does not
include all government-owned cables, such as those used for military and intelligence purposes.
An undersea telecommunication cable system includes two or more onshore terminal stations (or
cable landing stations) connected by a fiber-optic cable. The cable landing stations contain
transmission, reception, and network management equipment. The fiber-optic cable may include
repeaters within the cable that boost transmitted signals and branching units that allow a cable to
serve multiple end-points (Figure 2).

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Figure 2. Undersea Telecommunication Cable System

Source: Created by CRS.
Note: Graphic shows an undersea telecommunication cable system, including cable landing stations and
equipment (e.g., terminal equipment and power feed); undersea cable (with repeaters, and a branching unit)
running from beach manhole to beach manhole; and fiber lines from the cable landing station to a point-of-
presence that connects via fiber to inland terrestrial networks. POP=point-of-presence.
The following sections provide more detail on the segments of a cable system, including fiber-
optic cables, the terrestrial portion of an undersea telecommunication cable system called the “dry
plant,” and the undersea portion called the “wet plant.”
Dry Plant
The dry plant is the terrestrial segment of an undersea cable system, running from a cable landing
station to the beach manhole.21 A cable landing station is typically a few hundred meters from the
beach manhole near the shoreline and connected by a short, repeater-less fiber link.
Cable Landing Station
A cable landing station is an on-shore facility where undersea cables arrive and terminate.22 Cable
landing stations contain submarine line terminal equipment (SLTE) that can transmit and receive
signals. They receive signals from the undersea cable and transmit signals inland to terrestrial
networks, usually through a provider’s point-of-presence (POP) or interconnection facility, and
can receive signals from terrestrial networks and transmit them to undersea cables. Since a POP

21 Communications Security, Reliability and Interoperability (CSRIC) Working Group 4A Submarine Cable Resiliency,
Final Report―Clustering of Cables and Cable Landings (CSRIC WG4A—Final Report on Cable Landings), August
2016, p. 4, https://transition.fcc.gov/bureaus/pshs/advisory/csric5/WG4A_Final_091416.pdf.
22 Harry Newton, Newton’s Telecom Dictionary, 27th ed. (New York: Flatiron Publishing, 2013), p. 245.
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could be hundreds of miles from the seashore, operators often use a longer fiber link with
repeaters to connect to the cable landing station.23
To transmit signals, electronically controlled semiconductor lasers (laser diodes) transmit signals
by modulating (i.e., pulsing) light and sending it into the optical fiber. To receive signals,
semiconductor optical detectors receive the light from the fiber, modulate the signals to produce a
corresponding electrical signal, and transmit the signal to a provider’s POP or interconnection
facility, which transmits the signal to the provider’s terrestrial telecommunications network.
Cable landing stations may also contain network management systems that allow operators to
monitor and control cable operations and traffic, and power feed equipment (PFE) that provides a
constant direct electrical current through the cable to power repeaters.24
Beach Manhole
The beach manhole is a “concrete chamber, buried into the beach, or road behind the landing
point, where the submarine cable is terminated and from where the [fiber cable and power cable]
are routed to the [cable landing station]. Most manholes are designed to take more than one cable,
most commonly two.”25 Fiber connects the cable landing station to a beach manhole, where it
joins the undersea cable.
Wet Plant
The wet plant is the segment of the cable system that runs from a beach manhole on one landmass
to a beach manhole on another. Installation of new cables often requires boring and trenching to
place the manhole on or near the seashore and drilling beneath the beach to lay feeder pipes to
carry cables into the water. Special cable-laying ships, often equipped with a plough to dig a
trench in the seabed in which to lay cable, continue the installation from shore to shore.
Fiber-Optic Cable
Since the late 1980s, commercial undersea telecommunication cable owners have used optical
fibers—thin, flexible, and highly transparent glass or plastic strands—to facilitate long-distance
communications.26 Optical fibers allow signals to be sent over long distances using light pulses
instead of electricity, which, when compared with traditional copper lines, results in a clearer
signal, less signal loss over long distances, greater bandwidth, and less electromagnetic

23 Olivier Courtois and Caroline Bardelay-Guyot, “Architectures and Management of Submarine Networks,” Section
9.3.5 in Undersea Fiber Communication Systems, 2nd ed. (London: Academic Press, 2016).
24 Tomoyuki Kaneko, Yoshinori Chiba, and Kaneaki Kunimi, “Power Feeding Equipment for Optical Submarine,”
NEC Technical Journal, vol. 5, no. 1 (February 2010), pp. 28-32, https://mathscinotes.com/wp-content/uploads/2015/
03/PowerStuff.pdf; see also E.T. Calkin, I. Golioto, and W. Schatz, et al., “SG Undersea Cable System: Undersea
System Power,” Bell System Technical Journal, vol. 57, no. 7 (September 1978), pp. 2497-2522.
25 CSRIC WG4A—Final Report on Cable Landings, p. 4.
26 Earlier cables used copper wires to carry electrical signals; fiber-optic cables use light pulses to transmit digital data
in a binary format.
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interference.27 Due to these advantages, network architects assert that optical fiber is the best
physical medium to facilitate long distance communication and connect global networks.28
Optical fibers carry communications (e.g., voice, data, and internet) in the form of colored light
signals of various wavelengths (using a technique known as wavelength division multiplexing)29
to enable high-speed, long-distance communications.30 The optical fibers themselves are encased
in successive layers of materials to transmit power,31 and to strengthen and insulate the cable.
Figure 3 illustrates the bundled materials in a typical undersea fiber-optic cable.
Figure 3. Undersea Fiber-Optic Cable Cross-Section

Source: Oona Räisänen, Submarine Cable Cross-Section 3D Plain, Public Domain, accessed November 30, 2021,
https://commons.wikimedia.org/wiki/File:Submarine_cable_cross-section_3D_plain.svg.
Notes: (1) Polyethylene, (2) Mylar tape, (3) Stranded metal (steel) wires, (4) Aluminum water barrier, (5)
Polycarbonate, (6) Copper or aluminum tube, (7) Petroleum jelly, and (8) Optical fibers.

27 OptronicsPlus, Fibre Optics vs Copper Cabling—Understanding the Difference, White Paper,
https://optronicsplus.net/downloads/whitepapers/
OP_Fibre_Optics_vs_Copper_Cabling_Understanding_the_Difference_White_Paper_Rev.1.0.pdf.
28 Alessandro Maggio, “Physical Layer: Fiber Optic Media, Data as Light Pulses,” ICTShore, October 27, 2016,
https://www.ictshore.com/free-ccna-course/physical-layer-fiber-optic-media/.
29 In wavelength division multiplexing, multiple optical signals of different wavelengths (colors) are transmitted
together across a single fiber-optic cable and separated again for further routing, thus increasing the data transmission
capacity of the cable. See Charles A. Brackett, “Dense Wavelength Division Multiplexing Networks: Principles and
Applications,” IEEE Journal on Selected areas in Communications, vol. 8, no. 6 (August 1900), pp. 948-964; Klaus
Grobe, “Wavelength Division Multiplexing,” Encyclopedia of Modern Optics, ed. Bob D. Guenther and Duncan G.
Steel, 2 ed. (Elsevier, 2018), pp. 255-290, https://www.sciencedirect.com/science/article/pii/B9780128035818094716.
30 Jose Chesnoy, “Presentation of Submarine Fiber Communication,” in Undersea Fiber Communication Systems, ed.
Jose Chesnoy, 2nd ed. (London: Academic Press, 2016), p. 6.
31 Michael Morris, “The Incredible International Submarine Cable Systems,” Network World, April 19, 2009,
https://www.networkworld.com/article/2235353/the-incredible-international-submarine-cable-systems.html. (Repeaters
are powered by a constant direct current passed down a conductor near the center of the cable.)
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Multiple fiber optic cores (segments 5-8 in Figure 3) can be combined within the outer insulation
and strengthening layers (segments 1-4) of an undersea telecommunication cable. Near to the
shore, the cable is wrapped in tough shielding to protect against danger and damage from
activities occurring near to shore (e.g., fishing, shipping, and other marine activities).32 Undersea
cables can carry multiple fiber pairs, enabling numerous providers to use the same cable. Most
cables transmit in one direction on one fiber in a pair and in the reverse direction on the other.33
As optical signals pass from one segment of an undersea telecommunication cable to the next,
repeaters boost the signal with optical amplifiers using semiconductor laser pumps, allowing the
signal to travel long distances, and controlling the signal with optical equalizers to maintain its
integrity.34
Recent Technical Developments
Advances in fiber optic undersea cable technologies—for transmitting, receiving, and boosting
optical signals—have led average carrying capacity for undersea telecommunications signals to
increase from 25 to 60 terabits per second (Tbps) between 2014 and 2019.35 Recent technical
developments—system designs to allow integration of faster network equipment, increasing the
number of fiber pairs in a cable—have enabled undersea telecommunication cables to reach
carrying capacities of up to 250 Tbps.
The MAREA undersea cable operating between Virginia Beach, VA, and Bilbao, Spain, can
transmit up to 200 Tbps.36 When it was completed in 2017, its owners—Microsoft, Facebook and
Telxius (a subsidiary of Spanish telecommunications company, Telefónica)—stated that it was the
“highest-capacity subsea cable to ever cross the Atlantic—featuring eight fiber-pairs and an initial
estimated design capacity of 160 Tbps” operates “more than 16 million times faster than the
average home internet connection.”37 MAREA used an open design, which allows for the
integration of new, higher performing network equipment from a variety of makers into the
existing cable system as it is developed.38 In 2018, MAREA owners announced they had
integrated new technologies into the system, increasing its capacity from 160 Tbps to 200 Tbps.39

32 Doug Dawson, “Improvements in Undersea Fiber,” CCG Consulting (blog), September 30, 2021,
https://potsandpansbyccg.com/2021/09/30/improvements-in-undersea-fiber/.
33 The Fiber Optic Association, Inc., “Guide to Fiber Optics and Premises Cabling,” https://www.thefoa.org/tech/ref/
appln/OSPdatalink.html.
34 Jose Chesnoy, “Presentation of Submarine Fiber Communication,” in Undersea Fiber Communication Systems, ed.
Jose Chesnoy, 2nd ed. (London: Academic Press, 2016), p. 8.
35 Juha Saunavaar and Mirva Salmin, “Geography of the Global Submarine Fiber-Optic Cable Network: The Case for
Arctic Ocean Solutions,” Geographical Review, June 2020, pp. 1-9, https://www.tandfonline.com/doi/pdf/10.1080/
00167428.2020.1773266.
36 Telxius, “Telxius Operates the Two Highest Capacity Submarine Cables in the World,” press release, December 10,
2018, https://subtelforum.com/telxius-highest-capacity-cables/.
37 Suresh Kumar, “Celebrating the Completion of the Most Advanced Subsea Cable Across the Atlantic,” Official
Microsoft Blog, September 21, 2017, https://blogs.microsoft.com/blog/2017/09/21/celebrating-completion-advanced-
subsea-cable-across-atlantic/.
38 Deborah Bach, “Microsoft, Facebook and Telxius Complete the Highest-Capacity Subsea Cable to Cross the
Atlantic,” Microsoft Features, September 21, 2017, https://news.microsoft.com/features/microsoft-facebook-telxius-
complete-highest-capacity-subsea-cable-cross-atlantic/.
39 Winston Qiu, “MAREA Cable System Reaches 200 Tbps of Capacity,” Submarine Cable Networks, October 1,
2018, https://www.submarinenetworks.com/en/systems/trans-atlantic/marea/marea-cable-system-reaches-200-tbps-of-
capacity.
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In 2021, Google announced that its Dunant undersea cable between Virginia Beach, VA, and
Saint-Hilaire-de-Riez, France, was operational, with a carrying capacity of 250 Tbps.40 Google
reached this capacity using “space-division multiplexing” (SDM) technology. SDM increases
cable capacity in a cost-effective manner with additional fiber pairs (twelve, rather than the six or
eight in traditional subsea cables) and power-optimized repeater designs.41
Additionally, recent developments may allow undersea cables to serve multiple functions. The
University of Hawaii is a lead institution developing a global network of Science Monitoring And
Reliable Telecommunications (SMART) cables that integrate sensors that measure ocean
temperature, pressure, and seismicity into commercial undersea telecommunications networks to
enhance tsunami and earthquake early warning systems.42
Threats to Undersea Telecommunication Cables
Given the heavy reliance on undersea telecommunication cables for consumer, businesses, and
government communications, including some military communications, some U.S. officials,
industry stakeholders, and scholars have cited the need to protect them from damage. The
following section summarizes some of the threats posed to undersea telecommunication cables.
Unintentional Damage to Cables
There are a number of unintentional threats to the physical integrity of undersea
telecommunication cables, including commercial fishing and anchoring; natural disasters; and sea
life.43 Figure 4 presents International Cable Protection Committee (ICPC) data on the causes of
cable faults, based on analysis of fault data from 1959 to 2021.

40 Chris Ciauri, “The Dunant Subsea Cable, Connecting the US and Mainland Europe, Is Ready for Service,” Google,
February 3, 2021, https://cloud.google.com/blog/products/infrastructure/googles-dunant-subsea-cable-is-now-ready-
for-service.
41 Vijay Vusirikala, “A Quick Hop Across the Pond: Supercharging the Dunant Subsea Cable with SDM Technology,”
Google, April 5, 2019, https://cloud.google.com/blog/products/infrastructure/a-quick-hop-across-the-pond-
supercharging-the-dunant-subsea-cable-with-sdm-technology.
42 Marcie Grabowski, “Big Boost for Global Network of SMART Seafloor Cables, Early Warning Systems,”
University of Hawaii at Manoa, School of Ocean and Earth Science and Technology, December 15, 2021,
https://www.soest.hawaii.edu/soestwp/ announce/news/big-boost-for-global-network-of-smart-seafloor-cables-early-
warning-systems.
43 Jonathan E. Hillman, Securing the Subsea Network, A Primer for Policymakers, Center for Strategic and
International Studies, A Report of the CSIS Reconnecting Asia Project, March 2021, https://www.csis.org/analysis/
securing-subsea-network-primer-policymakers; see also ODNI Report, pp. 7-8.
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Figure 4. Cause of Undersea Telecommunication Cable Faults (1959 to 2021)

Source: Recreated by CRS, from Mike Clare, Submarine Cable Protection and the Environment, International Cable
Protection Committee (ICPC), March 2021, p. 7, https://www.iscpc.org/publications/submarine-cable-protection-
and-the-environment/ICPC_Public_EU_March%202021.pdf.
Notes: The original graphic was generated in 2021, based on analysis of data from a database of reported cable
damages kept since 1959. The ICPC report notes that the data was provided courtesy of Global Marine, a
British-headquartered company, which provides, installs, maintains, and repairs undersea telecommunications
cables.
Human Activities
The ICPC, a non-profit organization formed in 1958 to promote the protection of international
undersea telecommunications and power cables, estimates that human activities—fishing,
anchoring, and dredging, among others—accounted for roughly two-thirds of undersea cable
faults globally between 1959 and 2021.44 ODNI, in its 2017 report, Threats to Undersea Cable
Communications, stated that the majority of threats to cables are accidental incidents involving
humans.45 For example, a submarine telecommunication cable was accidentally severed by a ship
off the coast of Somalia in 2017, leading to a three-week internet outage costing the country $10
million a day according to a Somali government official.46
Natural Disasters
Although undersea telecommunication cables are infrequently damaged by natural disasters (e.g.,
earthquakes, tsunamis), the impacts of such incidents may be severe and long-lasting. For
example, on January 15, 2022, a volcanic eruption and earthquake severed Tonga’s only internet
connection—an undersea telecommunication cable that connects it to Fiji and other international

44 International Cable Protection Committee, Government Best Practices for Protecting and Promoting Resilience of
Submarine Telecommunications Cables, Version 1.1, https://www.iscpc.org/publications/icpc-best-practices/.
45 ODNI Report, p. 6.
46 “Somalia restores internet connection after weeks of outage,” Reuters, July 17, 2017, https://www.reuters.com/
article/us-somalia-internet-restored/somalia-restores-internet-connection-after-weeks-of-outage-idUSKBN1A21P6; see
also Associated Press, “Somalia back online after entire country cut off from internet for three weeks,” The Guardian,
July 17, 2017, https://www.theguardian.com/world/2017/jul/18/somalia-cut-off-from-internet-entire-country-three-
weeks.
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networks47—which took five weeks to fully restore.48 During the outage mobile network
providers offered some connectivity to customers on the main island (where most of the
population lives) using satellite connections, although customers reported that capacity was
limited, affecting their ability to communicate, connect to the internet, and conduct financial
transactions.49 While repair ships replaced the 56 miles of the international cable connecting
Tonga to Fiji (and the rest of the world), the domestic cable, connecting Tonga to its outer islands
and the outer islands to each other, is still under repair. In March 2022, Tonga Cable Ltd., Tonga’s
state-owned cable owner, stated the repairs could take up to a year.50
Intentional Damage to Undersea Telecommunication Cables
Some in Congress have expressed concerns over intentional damage to commercial or
government-owned undersea telecommunication cables by foreign adversaries and bad actors
seeking to disrupt communications or gather personal, corporate, or government information.51
In 2017, ODNI reported that while there had been few reported attacks on undersea
telecommunication cables, some had been long lasting and impactful. In 2007, Vietnamese pirates
stole optical amplifiers, disabling a cable system for 79 days.52 In 2013, a diver intentionally cut
the South East Asia-Middle East-Western-Europe 4 (SMW 4) cable, affecting several service
providers, slowing internet speeds by 60% in Egypt.53 The ODNI report stated that signal
rerouting technologies, redundancies in cable lines, and networks of repair ships had increased
resiliency of undersea cable networks and reduced the potential that a single cut would cause
widespread outages.54 Further, it asserted that simultaneous attacks against multiple cables could
cause “serious long-term disruption,”55 but are difficult to carry out.
Some North Atlantic Treaty Organization (NATO) defense officials and other foreign affairs
analysts have expressed concern that Russia could cut commercial undersea telecommunication
cables to disrupt communications.56 In 2017, U.S. Navy Rear Admiral Andrew Lennon,

47 TeleGeography, “Tonga Cable,” https://www.submarinecablemap.com/submarine-cable/tonga-cable.
48 Associated Press, “Tonga’s Internet Is Restored 5 Weeks After Big Volcanic Eruption,” NPR.org, February 22, 2022,
https://www.npr.org/2022/02/22/1082483555/tongas-internet-restored-5-weeks-after-big-eruption.
49 Chris Duckett, “Digicel Reconnects Tongan Users via Satellite to Rest of the World,” ZDNet, January 19, 2022,
https://www.zdnet.com/home-and-office/networking/digicel-reconnects-tongan-users-via-satellite-to-rest-of-the-world/.
50 Linny Folau and Mary Lyn Fonua, “Torn Apart, Missing 110km Domestic Fibre Optic Cable May Take Year to
Replace,” Matangi Tonga Online, March 1, 2022, https://matangitonga.to/2022/03/01/torn-apart-missing-fibre-optic-
domestic-cable-Tonga.
51 ODNI Report, p. 22; Morgan Chalfant and Olivia Beavers, “Spotlight Falls on Russian Threat to Undersea Cables,”
The Hill, June 17, 2018, https://thehill.com/policy/cybersecurity/392577-spotlight-falls-on-russian-threat-to-undersea-
cables/; see also “Concern over Russian Ships Lurking Around Vital Undersea Cables,” CBS News, March 30, 2018,
https://www.cbsnews.com/news/russian-ships-undersea-cables-concern-vladimir-putin-yantar-ship/; and David E.
Sanger and Eric Schmitt, “Russian Ships Near Data Cables Are Too Close for U.S. Comfort,” New York Times,
October 26, 2015, https://www.nytimes.com/2015/10/26/world/europe/russian-presence-near-undersea-cables-
concerns-us.html.
52 ODNI Report, p. 13.
53 Ibid.
54 Ibid, p. 7.
55 Ibid, p. 8.
56 Michael Birnbaum, “Russian Submarines Are Prowling Around Vital Undersea Cables. It’s Making NATO
Nervous,” Washington Post, December 22, 2017, https://www.washingtonpost.com/world/europe/russian-submarines-
are-prowling-around-vital-undersea-cables-its-making-nato-nervous/2017/12/22/d4c1f3da-e5d0-11e7-927a-
e72eac1e73b6_story.html; Justin Sherman, “Cord-Cutting, Russian Style: Could the Kremlin Sever Global Internet
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commander of NATO’s submarine forces at the time, reportedly stated, “We are now seeing
Russian underwater activity in the vicinity of undersea cables that I don’t believe we have ever
seen ... Russia is clearly taking an interest in NATO and NATO nations’ undersea
infrastructure.”57 In 2018, one media outlet, citing a Russian parliamentary publication, reported
on Russian capabilities to tap top-secret communication cables, cut undersea cables, and jam
underwater sensors.58 According to an industry expert, “If somebody knew how these systems
worked and if they staged an attack in the right way, then they could disrupt the entire system.
But the likelihood of that happening is very small.”59
Repairing Damaged Undersea Telecommunications Cables
Monitoring and repairing commercial undersea telecommunication has generally been the
responsibility of the private sector owner/operator(s) of those cables. When a cable is damaged,
phone and internet service may be disrupted in certain regions on either end of the cable; service
providers often reroute traffic to redundant lines, if available. Cable owners generally test
damaged cables from shore by sending a light pulse along the fibers in the cable, which bounces
back from the site of the damage.60 By measuring the time it takes for the light pulse to return,
engineers can determine the general area of outage.
Owners rely on commercial cable ships and crews, carrying specialized equipment (e.g.,
technology to find the exact location of the break, remotely operated submersible vehicles,
grappling tools to pull the cable to the surface) to locate, raise, repair, test, and replace the cable
to the seabed.61 In some cases, cable owners’ companies agree to carry traffic for each other in
event of a cable break, to avoid disruptions in service.62 In other cases, cable owners employ
engineers to conduct or oversee the maintenance and repair of cable that it owns or leases, or
contract with a commercial company for repairs; during repairs, it may switch traffic to another
route to avoid service disruptions.63 About 70 cable owners are members of the Atlantic Cable
Maintenance and Repair Agreement (ACMA), a non-profit cooperative subsea maintenance

Cables?,” New Atlanticist (blog), January 31, 2022, https://www.atlanticcouncil.org/blogs/new-atlanticist/cord-cutting-
russian-style-could-the-kremlin-sever-global-internet-cables/; Sebastian Seibt, “Threat Looms of Russian Attack on
Undersea Cables to Shut Down West’s Internet,” France 24 News, March 23, 2022, https://www.france24.com/en/
europe/20220323-threat-looms-of-russian-attack-on-undersea-cables-to-shut-down-west-s-internet.
57 Michael Birnbaum, “Russian Submarines Are Prowling Around Vital Undersea Cables. It’s Making NATO
Nervous,” Washington Post, December 22, 2017, https://www.washingtonpost.com/world/europe/russian-submarines-
are-prowling-around-vital-undersea-cables-its-making-nato-nervous/2017/12/22/d4c1f3da-e5d0-11e7-927a-
e72eac1e73b6_story.html.
58 Deb Reichmann, “Could Enemies Target Undersea Cables That Link the World?,” AP News, March 30, 2018,
https://apnews.com/article/moscow-north-america-ap-top-news-politics-russia-c2e7621bda224e2db2f8c654c9203a09.
59 Louise Matsakis, “What Would Really Happen If Russia Attacked Undersea Internet Cables,” Wired, January 5,
2018, https://www.wired.com/story/russia-undersea-internet-cables/.
60 Lindsay Goldwert, “How Do You Fix an Undersea Cable?,” Slate, January 8, 2007, https://slate.com/news-and-
politics/2007/01/how-do-you-fix-an-undersea-cable.html.
61 Eric Wagner, “30,000 Feet Below: Connecting Continents from the Ocean Floor,” AT&T Technology Blog, June 1,
2017, https://about.att.com/innovationblog/undersea_cables.
62 CSRIC IV, Working Group 8, Submarine Cable Routing and Landing, Final Report—Protection of Submarine
Cables through Spatial Separation (CSRIC WG8 Spatial Separation Report), December 2014, p. 46,
https://transition.fcc.gov/pshs/advisory/csric4/CSRIC_IV_WG8_Report1_3Dec2014.pdf.
63 John Brandon, “Protecting the Submarine Cables That Wire Our World,” Popular Mechanics, March 15, 2013.
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agreement, that offers, among other things, a fleet dedicated to the maintenance of members’
cables.64
Cyberattacks
Global internet and telecommunications traffic is routed and transported through the undersea
telecommunication cable network using advanced information and communication technologies
and network management software, making the system vulnerable to cyberattacks. A 2021 think
tank report notes that, “more companies are using remote management systems for submarine
cable networks—tools to remotely monitor and control cable systems over the Internet—which
are cost-compelling because they virtualize and possibly automate the monitoring of cable
functionality.”65 However, these tools (e.g., software, remote management systems) may create
new risks to cable security and resilience.66 Hackers could access cables through network
management systems to skim personal or financial information, hold network management
systems hostage until operators pay ransom, or cause widespread disruption in communications.67
In April 2022, U.S. Department of Homeland Security Investigations (DHSI) reportedly thwarted
a cyberattack on a network of a company that manages an undersea telecommunication cable that
provides internet and mobile phone services in Hawaii and in countries across the Pacific
region.68 DHSI officials attributed the attack to an international hacking group, but were not
certain of the intent—whether the attacker intended to access business or personal information,
hold the system for ransom, or to disrupt communications.69 DHSI reportedly worked with law
enforcement agencies in several countries to make an arrest.70
U.S. Actions to Protect Cables
The U.S. government has taken action to protect undersea telecommunication cables. It reviews
ownership of cables landing in the United States to identify and mitigate security concerns. It
restricts the use of certain vendors and equipment in cables landing in the United States and
encourages its allies and partners to do the same. It monitors cables to detect attacks. It invests in
cable repair ships to address damage.

64 ACMA, “FAQs,” available at https://www.acma2017.com/about/faqs/.
65 Justin Sherman, Cyber Defense Across the Ocean Floor: The Geopolitics of Submarine Cable Security, Atlantic
Council Scowcroft Center for Strategy and Security, September 13, 2021.
66 Ibid. (The report states that hackers could “breach multiple remote network management systems used to control
different submarine cables to completely disrupt the flow of Internet data across that infrastructure.” It also notes that
hacking a submarine cable may be easier than physically tapping cables, as it can be done remotely.)
67 Justin Sherman, “The U.S. Should Get Serious About Submarine Cable Security,” Council on Foreign Relations
(blog), September 13, 2021, https://www.cfr.org/blog/us-should-get-serious-about-submarine-cable-security.
68 CyberTalk, “Hawaii Undersea Cable Attack: A Credential Theft Story,” April 22, 2022.
69 Hawaii News Now, “Federal Agents Disrupted Cyberattack Targeting Phone, Internet Infrastructure on Oahu,” April
12, 2022, https://www.hawaiinewsnow.com/2022/04/13/hsi-agents-honolulu-disrupted-cyberattack-undersea-cable-
critical-telecommunications/.
70 Peter Boylan, “Cyberattack on Hawaii Undersea Communications Cable Thwarted by Homeland Security,” Star
Advertiser, April 12, 2022, https://www.staradvertiser.com/2022/04/12/breaking-news/cyberattack-on-hawaii-
undersea-communications-cable-thwarted-by-homeland-security/.
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Foreign Ownership Review
To operate a cable in the United States, operators must obtain a cable landing license from the
FCC. Pursuant to its authorities under the Cable Landing License Act of 192171 and Executive
Order 10530,72 the FCC has authority to issue, withhold, or revoke licenses to land or operate
commercial undersea telecommunication cables in the United States, provided no such license
shall be granted or revoked by the FCC until obtaining approval from the Secretary of State and
advice from any executive department the FCC deems necessary.
Additionally, commercial undersea telecommunication cable operators may need to obtain
authority to provide international telecommunication services, as required under Section 214 of
the Communications Act of 1934, as amended (“the Act”).73 Further, cable operators that co-
invest with other entities may need to report foreign ownership interests in undersea cables, if
foreign ownership exceeds 10%, as required under Section 310(b) of the act.74
When foreign ownership exceeds 10%, the FCC refers the applicant to a group of national
security agencies,75 commonly (and unofficially) known as Team Telecom. Team Telecom
reviews applications for national security and foreign affairs concerns, and makes
recommendations to the FCC to inform its licensing decisions. On April 4, 2020, President Trump
issued Executive Order 13913, which formalized the Team Telecom review process, expanded its
membership,76 and renamed Team Telecom the Committee for the Assessment of Foreign
Participation in the United States Telecommunications Services Sector.77
In June 2020, DOJ released a statement announcing that Team Telecom recommended the FCC
partially deny the Pacific Light Cable Network (PLCN) undersea telecommunication cable
system application, due to national security concerns.78 Team Telecom recommended approval of
part of the cable—that which was owned and controlled by Google and Facebook, seeking to
connect the United States, Taiwan, and the Philippines. It denied the direct connection between
the United States and Hong Kong, due to national security and foreign ownership concerns. In
August 2020, Google and Meta (formerly Facebook) revised their cable license, eliminating the
connection to Hong Kong.79 In December 2021, Team Telecom recommended that the FCC grant

71 47 U.S. Code Chapter 2.
72 National Archives, Office of the Federal Register, “Executive Orders” (Executive Order 10530, Part IV),
https://www.archives.gov/federal-register/codification/executive-order/10530.html.
73 47 U.S.C. §214.
74 47 U.S.C. §310(b).
75 Team Telecom included the Departments of Defense, Homeland Security, and Justice (including the Federal Bureau
of Investigation), and consultations with other agencies as needed.
76 The Committee is chaired by the Attorney General and includes the Secretaries of Defense and Homeland Security;
Advisors to the Committee are the Secretaries of Commerce, State, and Treasury; Director of National Intelligence;
Administrator of General Services; Director of the Office of Management and Budget; Director of the Office of
Science and Technology; U.S. Trade Representative; National Security Adviser; Chair of the Council of Economic
Advisers; and Assistant to the President for Economic Policy.
77 Executive Office of the President, “Establishing the Committee for the Assessment of Foreign Participation in the
United States Telecommunications Services Sector,” 85 Federal Register 19643-19650, April 4, 2020.
78 DOJ, “Team Telecom Recommends that the FCC Deny Pacific Light Cable Network System’s Hong Kong Undersea
Cable Connection to the United States,” press release, June 17, 2020, https://www.justice.gov/opa/pr/team-telecom-
recommends-fcc-deny-pacific-light-cable-network-system-s-hong-kong-undersea.
79 Todd Shields, “Google, Facebook Dump Plans for U.S.-Hong Kong Undersea Cable,” Bloomberg, August 28, 2020,
https://www.bloomberg.com/news/articles/2020-08-29/google-facebook-dump-hong-kong-cable-after-u-s-security-
alarm#xj4y7vzkg.
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Google and Meta licenses for their revised cable application.80 The U.S. government entered into
a National Security Agreement with Google and Meta to protect personal data, pursue
diversification of interconnection points between the United States and Asia, and restrict access to
information and infrastructure by the China-based PLCN partner, Pacific Light Data
Communications.81 In February 2022, the FCC approved the cable landing license for the PLCN
connecting the United States to Taiwan and the Philippines.82
Restrict Use of Untrusted Equipment
In 2018, the U.S. government identified telecommunication vendors that pose a threat to the
national security and foreign policy interest of the United States.83 In Section 889 of the John S.
McCain National Defense and Authorization Act of FY2019 (NDAA, FY2019, P.L. 115-232),
Congress named five Chinese equipment-makers as companies “covered” by the restrictions in
the law. The law prohibited federal agencies from purchasing equipment or obtaining equipment
or systems that use the “covered” equipment; entering into a contract with an entity that uses
“covered” equipment; or awarding grants or providing loans for “covered” equipment. The
assertion was that the vendors and equipment were untrusted, and if U.S. agencies or grantees
installed untrusted equipment in U.S. networks, the Chinese government could potentially capture
critical data by compelling vendors to deliver the data to them, or using the equipment to commit
espionage against the United States.
Among the vendors named in Section 889 was Huawei Technologies Company (Huawei).
Huawei is the world’s largest telecommunication network equipment supplier. It makes wireless
network equipment (e.g., 4G, 5G), mobile phones, and undersea telecommunication cable
equipment, among other things. Its undersea cable segment—Huawei Marine Networks—was
among the top five suppliers in the global undersea cable equipment market.84 By some accounts,
it has built or repaired almost a quarter of the world’s cables, including upgrades to a cable
connecting the United States and Canada, and a cable connecting New York City and London.85
In May 2019, the Department of Commerce (DOC) identified Huawei as an entity posing a threat
to the national security and foreign policy interests of the United States. DOC cited a Superseding
Indictment filed in the Eastern District of New York, alleging that Huawei sold U.S. goods to
Iran, violating U.S. sanctions, and engaged in deceptive acts to evade U.S. law.86 DOC added

80 DOJ, “Team Telecom Recommends FCC Grant Google and Meta Licenses for Undersea Cable,” press release,
December 17, 2021, https://www.justice.gov/opa/pr/team-telecom-recommends-fcc-grant-google-and-meta-licenses-
undersea-cable.
81 DOJ, “National Security Agreement,” December 13, 2021, https://www.justice.gov/opa/press-release/file/1457291/
download.
82 FCC, “FCC Approves Licenses for PLCN,” February 13, 2022, https://www.submarinenetworks.com/en/systems/
trans-pacific/plcn/fcc-approves-license-for-plcn.
83 CRS Report R47012, U.S. Restrictions on Huawei Technologies: National Security, Foreign Policy, and Economic
Interests, by Jill C. Gallagher.
84 Rebecca Spence, Industry Report 2021/2022, Submarine Telecoms Forum, Issue 10, October 25, 2021, p. 50,
https://subtelforum.com/products/submarine-telecoms-industry-report/.
85 Nadia Schadlow and Brayden Helwig, “Protecting Undersea Cables Must Be Made a National Security Priority,”
Defense News, July 1, 2020, https://www.defensenews.com/opinion/commentary/2020/07/01/protecting-undersea-
cables-must-be-made-a-national-security-priority/.
86 DOJ, “Chinese Telecommunications Conglomerate Huawei and Huawei CFO Wanzhou Meng Charged with
Financial Fraud,” press release, January 28, 2019, https://www.justice.gov/opa/pr/chinese-telecommunications-
conglomerate-huawei-and-huawei-cfo-wanzhou-meng-charged-financial; and DOC, Bureau of Industry and Security,
“Addition of Entities to the Entity List,” 84 Federal Register 22961-22968, May 21, 2019, https://www.bis.doc.gov/
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Huawei to the Bureau of Industry and Security Entity List, which restricts the “export, reexport,
and in-country transfer of [U.S.] technology” to listed firms.87 In response, Huawei sold shares in
and segments of its business, including its undersea cable business.88 The Chinese fiber-optic firm
Hengteng Optic Electric purchased Huawei Marine in November 2020, and renamed it HMN
Technologies Co., Ltd.89 Due to the name change, it was able to operate for nearly a year, without
restrictions, until the DOC placed HMN Technologies on the Entity List in December 2021.90
In 2018, the U.S. Treasury Department designated five Russian entities and several individuals as
“covered” for providing material and technological support to Russia’s Federal Security Service,
known as FSB.91 Treasury states that since 2007, one of the firms, Divetechnoservices, has
procured a variety of underwater equipment and diving systems for Russian government
agencies, including the FSB. In 2011, Divetechnoservices was awarded a contract to procure a
submersible craft valued at $1.5 million for the FSB. Treasury notes that Russia has been active in
tracking undersea communication cables, and Divetechnoservices has contributed to improving
Russia’s cyber and underwater capabilities, which jeopardize the safety and security of the United
States and its allies. For this reason, Treasury added Divetechnoservices and several of its officers
to the Entity List for providing material and technological support to the FSB.
In 2022, after Russia invaded Ukraine, the U.S. government took additional action on Russian
companies and individuals supporting the FSB. Treasury asserted that an individual set up a front
company in Finland to evade U.S. sanctions and procure underwater dive equipment for
Divetechnoservices to support the FSB and to improve Russia’s cyber and underwater
capabilities.92 Treasury added both the individual and the front company to the Entity List.
Facilitate Investment in Trusted Equipment
Under the Trump Administration, the State Department established the Clean Network Program,93
which aimed to secure global networks in five areas: U.S. telecommunication networks, mobile
application stores, software applications, cloud computing, and undersea cables. The Biden
Administration is pursuing similar efforts to build global consensus on network security and
encourage the use of trusted equipment and applications and financing alternatives to Chinese-
made equipment and undersea telecommunication cables and services. For example, in December
2021, the State Department announced an agreement between Australia, Japan, and the United

index.php/documents/regulations-docs/2394-huawei-and-affiliates-entity-list-rule/file.
87 DOC, Bureau of Industry and Security, “Addition of Certain Entities to the Entity List and Revision of an Entry on
the Entity List,” 86 Federal Register 71557-71568, December 17, 2021.
88 Huawei Marine Networks is also known as Huawei Marine, HMN Technologies, and HMN Tech.
89 HMN Tech, “Huawei Marine Networks Rebrands as HMN Technologies,” press release, November 3, 2020,
https://www.hmntechnologies.com/enPressReleases/37764.jhtml.
90 DOC, Bureau of Industry and Security, “Addition of Certain Entities to the Entity List and Revision of an Entry on
the Entity List,” 86 Federal Register 71559, December 17, 2021.
91 U.S. Department of the Treasury, “Treasury Sanctions Russian Federal Security Service Enablers,” press release,
June 11, 2018.https://home.treasury.gov/news/press-releases/sm0410.
92 U.S. Department of Treasury, “Treasury Targets Sanctions Evasion Networks and Russian Technology Companies
Enabling Putin’s War,” press release, March 31, 2022, https://home.treasury.gov/news/press-releases/jy0692.
93 U.S. Department of State, “The Clean Network (archived content),” https://2017-2021.state.gov/the-clean-network/
index.html. The Clean Network was announced by then-Secretary of State Mike Pompeo in August 2020.
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States, working in partnership with the Federated States of Micronesia, and with financing from
the World Bank and the Asian Development Bank, to build an undersea cable.94
On June 26, 2022, President Biden announced a new initiative formed at the 2021 G7 Summit, to
launch the Partnership for Global Infrastructure and Investment (PGII).95 Some see the PGII as a
counter to China’s Belt and Road Initiative (BRI)—its infrastructure investment program to
enhance physical and digital connections between China and the rest of the world, to facilitate
trade and economic growth.96 Similarly, the PGII would mobilize hundreds of billions of dollars
for “infrastructure that makes a difference in people’s lives around the world, strengthens and
diversifies our supply chains, creates new opportunities for American workers and businesses,
and advances our national security.”97 Under PGII, a $600 million contract to build an undersea
telecommunication cable connecting Singapore to France through Egypt and the Horn of Africa
was awarded to U.S. cable company SubCom.98
Enhance Cable Security Review
In September 2021, the FCC adopted a set of standardized national security questions that
undersea telecommunication cable license applicants with foreign ownership are required to
answer and submit directly to the executive branch agencies prior to or at the same time they file
their application.99 The questions address physical and cyber security topics such as network
controls access, communications content access, encryption use, and network peering
connections.100 The FCC commissioners agreed that these actions improve the executive branch
review process and provide the federal government with needed information for a comprehensive
security review.101 Commissioners Jessica Rosenworcel and Geoffrey Starks urged the FCC to
monitor networks beyond the application process to ensure network security and resiliency.102

94 U.S. Department of State, “Joint Statement on Improving East Micronesia Telecommunications Connectivity,” press
release, December 11, 2021, https://www.state.gov/joint-statement-on-improving-east-micronesia-telecommunications-
connectivity/.
95 The White House, “FACT SHEET: President Biden and G7 Leaders Formally Launch the Partnership for Global
Infrastructure and Investment,” statements and releases, June 26, 2022, https://www.whitehouse.gov/briefing-room/
statements-releases/2022/06/26/fact-sheet-president-biden-and-g7-leaders-formally-launch-the-partnership-for-global-
infrastructure-and-investment/.
96 CRS In Focus IF11735, China’s “One Belt, One Road” Initiative: Economic Issues, by Karen M. Sutter, Andres B.
Schwarzenberg, and Michael D. Sutherland. See also “The G7 at last presents an alternative to China’s Belt and Road
Initiative,” The Economist, July 7, 2022, https://www.economist.com/china/2022/07/07/the-g7-at-last-presents-an-
alternative-to-chinas-belt-and-road-initiative.
97 The White House, “FACT SHEET: President Biden and G7 Leaders Formally Launch the Partnership for Global
Infrastructure and Investment,” statements and releases, June 26, 2022.
98 Ibid.
99 FCC, “Process Reform for Executive Branch Review of Certain FCC Applications and Petitions Involving Foreign
Ownership.” 85 Federal Register 7, November 27, 2020.
100 Ibid, p. 76361 (fn. 4).
101 See FCC Commissioners statements at FCC, “FCC Improves Transparency and Timeliness of Foreign Ownership
Review,” October 1, 2020, https://www.fcc.gov/document/fcc-improves-transparency-and-timeliness-foreign-
ownership-review.
102 Ibid.
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Monitor Cable Outages
On October 28, 2021, the FCC began requiring submarine cable operators to report specified
unplanned service outages or degradation.103 The FCC collects information through its Network
Outage Reporting System to facilitate its “monitoring, analysis, and investigation of the reliability
and security of submarine cable networks, and to identify and take action on potential threats to
our Nation’s telecommunications infrastructure.”104
Both private owner/operators of undersea telecommunication cables and U.S. agencies actively
monitor networks for cyberattacks. The DHSI Cyber Crimes Center works with private sector
targets of cyberattacks and international partners, “coordinates investigations of cyber-related
criminal activity, and brings together highly technical assets dedicated to conducting trans-border
criminal investigations of cyber-related crimes.”105
Identify Policies and Standards to Protect Cables
The Communications Security, Reliability and Interoperability Council (CSRIC), an FCC
advisory committee, whose members include technical experts from the telecommunication
industry and federal agencies, published several reports with a series of recommendations to
improve undersea cable security. These include the creation of cable protection zones; improved
interagency coordination on cable routing; the diversification of routes to increase resiliency and
redundancy; the creation of spatial separation requirements or standards to avoid damage from
competing marine activities (e.g., installation of power cables and wind farms); and coordination
between federal, state, and local agencies and industry (e.g., fishing, shipping) to improve
awareness of undersea telecommunication cable vulnerabilities and security needs.106
Invest in Cable Repair Vessels
Commercial undersea telecommunication cable owners rely on global private sector companies to
lay, maintain, and repair cables. Industry watchers report that with increased demand for undersea
cable deployment, installation and repair fleets are booked for several years, which could limit
their availability for maintenance and repair of existing cables.107 While the U.S. government had
a ship capable of laying and repairing cable (USNS Zeus),108 some scholars urged the U.S.
government to build its repair capacity, and to take more responsibility for repairing cables to

103 FCC, “Improving Outage Reporting for Submarine Cables and Enhanced Submarine Cable Outage Data,” 86
Federal Register 22360, April 28, 2021; see also FCC, “Public Safety and Homeland Security Bureau Reminds
Submarine Cable Operators of Effective Date of New Outage Reporting Rules,” October 28, 2021,
https://www.fcc.gov/document/new-submarine-cable-outage-reporting-rules-effective-today.
104 Ibid, p. 22361.
105 U.S. Department of Homeland Security, “HSI Cyber Crimes Center,” https://www.ice.gov/partnerships-centers/
cyber-crimes-center.
106 For a list of CSRIC reports, see https://www.fcc.gov/CSRICReports.
107 Rebecca Spence, “Where in the World Are Those Pesky Cable Ships? July 2021,” Submarine Telecoms Forum, July
23, 2021, https://subtelforum.com/where-in-the-world-are-those-pesky-cable-ships-july-2021/.
108 Naval Facilities Engineering Systems Command, “Naval Seafloor Cable Protection Office (NSCPO),”
https://www.navfac.navy.mil/products_and_services/dc/products_and_services/naval_ocean_facilities_program/
sea_floor_cable_protection_nscpo/nscpo_background.html. (The U.S. Navy owns 40,000 miles of undersea cables and
maintains a single cable ship—USNS Zeus—through the Military Sealift Command, which conducts oceanographic
survey and the installation and maintenance of submarine cable systems.)
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protect national security.109 In the NDAA for Fiscal Year 2020 (P.L. 116-92), the U.S. government
authorized funding for a Cable Security Program, through which the U.S. government pays for
the option to deploy commercial ships in times of emergencies. Through the program, the U.S.
government provided $10 million to two privately owned, U.S. flagged ships,110 each subsidized
at $5 million per year, to continuously operate the vessels in the commercial submarine cable
services market (including the laying, maintenance, and repair of submarine cables) and provide
the U.S. government access to the vessels in times of national emergency.111 The intent of the
program is to meet national security requirements and to maintain a U.S. presence in the
international submarine cable services market.112
Issues for Congress
Given the importance of commercial undersea telecommunication cables to consumer, business,
and government communications, Congress may consider several policy options to address risks
to the commercial undersea telecommunication cable network.
Role of U.S. Government in Protection of Cables
Congress may consider the role of the U.S. government in securing commercial undersea
telecommunication cables. The DHS Communications Sector Specific Plan, issued in 2015 by
DHS, emphasizes the need to work with the private sector to ensure the security and resiliency of
communication systems. The Plan focuses on fiber networks serving communities and businesses
with broadband services, but does not mention undersea telecommunication cables specifically.113
Congress could direct DHS to update its Communications Sector Specific Plan and related
Information Technology Sector-Specific Plan, and include specific recommendations for
enhancing security and resiliency of undersea cables. Congress could establish a formal
framework to ensure security of cables, similar to that used for pipelines, under the Transportation
Security Administration within DHS.114
Congress may consider the recommendations of the CSRIC to appoint a lead agency to
coordinate undersea telecommunication cable security, or establish an interagency working group

109 Nadia Schadlow and Brayden Helwig, “Protecting Undersea Cables Must Be Made a National Security Priority,”
Defense News, July 1, 2020, https://www.defensenews.com/opinion/commentary/2020/07/01/protecting-undersea-
cables-must-be-made-a-national-security-priority/. See also Bert Chapman, Undersea Cables: The Ultimate
Geopolitical Chokepoint, Purdue University, FORCES Initiative: Strategy, Security, and Social Systems, December 13,
2021, p. 9, https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1000&context=forces. Citing an unintentional cut in
three undersea cables connecting Italy and Egypt, disrupting 80% of the connectivity between Europe and the Middle
East, the author states this was “particularly problematic for the U.S. and British militaries, which had 200,000 troops
in Iraq at that time and relied on commercial undersea cable networks for 95% of their strategic communications,”
demonstrating the national security concern.
110 U.S.-flagged vessel means any vessel registered under the laws of the United States (26 U.S.C. §1355).
111 Department of Transportation, Maritime Administration, “Request for Application to be Considered for Enrollment
in the Cable Security Fleet,” 86 Federal Register 355, January 5, 2021.
112 For more information, see CRS Report R46654, U.S. Maritime Administration (MARAD) Shipping and Shipbuilding
Support Programs, by Ben Goldman. See also “C.S. Decisive reflagged for U.S. Cable Security Fleet,” American
Maritime Officer (Vol. 52, No. 2), February 2022, https://www.amo-union.org/news/2022/202202/202202.pdf. (Noting
that SubCom’s cable ship, C.S. Dependable was reflagged into U.S. registry in December 2021 and SubCom’s cable
ship, Decisive, was reflagged into U.S. registry in January 2022 for service in the two-ship U.S. Cable Security Fleet.)
113 DHS, Communications Sector-Specific Plan: An Annex to the NIPP 2013, 2015, https://www.cisa.gov/sites/default/
files/publications/nipp-ssp-communications-2015-508.pdf.
114 For further details, see CRS Report R46903, Pipeline Cybersecurity: Federal Programs, by Paul W. Parfomak and
Chris Jaikaran.
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to coordinate cable security to increase its oversight of cables and cable technologies. It could
extend FCC’s authorities to ensure security of new and existing cables, coordinate federal agency
review of cable applications, and disseminate undersea cable security information to other federal
agencies. Congress could also consider a recommendation contained in the 2017 ODNI report to
delegate authority to an agency to build public-private partnerships to secure cables, to set
standards for security, and promote those standards globally. Alternatively, it may conclude that
no further action is needed and continue to rely on the private sector and private agreements for
protection of commercial cables.
Another approach could be to increase the number of landing stations in the United States to
attract new cables and to increase the resiliency and redundancy of the U.S. telecommunication
network. Some Members have proposed legislation to incentivize states to build cable landing
stations, as in S. 1166, introduced in the 116th Congress. The Infrastructure Investment and Jobs
Act (P.L. 117-58) includes undersea telecommunications cables and landing stations as an
allowable expense under Middle Mile Grant Program, funded under the act.
Connections with Adversarial Nations
Congress may consider whether the U.S. government should restrict U.S. firms from constructing
undersea telecommunication cables that connect the United States to the territory of adversarial
nations or from entering into partnerships with companies from those countries. Congress could
continue to rely on the existing process whereby the FCC refers applications to Team Telecom for
review, where Team Telecom reviews undersea cable license applications and identifies national
security concerns for the FCC, and the FCC considers Team Telecom recommendations in its
decision to approve, deny, modify, or condition any license application. Some Members have
proposed legislation, such as in H.R. 4029 (117th Congress), to codify the Team Telecom national
security review process and to increase interagency coordination.
Some security experts assert that landing a cable in an adversarial nation may increase an
adversary’s ability to tap or intercept sensitive commercial and private information and should be
restricted. However, restricting connections to specific countries could affect economic gains for
U.S. companies. For example, in the Asia-Pacific region, submarine cables have typically landed
in one of a few hubs, including Japan, Singapore, and Hong Kong. Since cables commonly land
in these hubs, data centers are also concentrated there. Limiting the ability of U.S. companies to
land cables in Hong Kong, or to access data centers in Hong Kong, could limit their ability to
serve the Hong Kong market or beyond. Limiting connections between the United States and
China may force Chinese companies to connect cables to countries other than the United States
and to move their data centers or spur new data centers near those cable landing stations.
A 2020 report published by Johns Hopkins Applied Physical Laboratory asserts that restricting
the participation of U.S. firms in undersea cable projects that connect the United States to a
Chinese territory could reduce “the availability and resilience of network connectivity between
the United States and the Asia Pacific [region]” and that “global data storage and processing
capacities would potentially migrate out of the United States.”115 Congress may consider how to
best mitigate national security concerns associated with commercial undersea cable projects that
land in the territories of nations deemed to be adversarial to the interests of the United States,
while addressing potential economic impacts of those mitigation measures.

115 Paul Triolo, The Telecommunications Industry in U.S.-China Context: Evolving Toward Near-Complete Bifurcation,
The Johns Hopkins Applied Physics Laboratory, 2020, pp. 16-17, https://apps.dtic.mil/sti/pdfs/AD1116899.pdf.
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Restrictions on Technologies or Technology Firms
Congress may consider additional restrictions on any cable terminating in U.S. territory from
containing equipment from adversarial nations. While additional restrictions may curb the use of
this equipment in new cables, they do not address the presence of untrusted equipment in existing
undersea cable networks. Thus, Congress may also consider increased support for monitoring
existing cables terminating in U.S. territory and investing in the development of new technologies
for monitoring or defending against a cyberattack on existing undersea telecommunication cables.
Strengthening Security Requirements
Congress could strengthen or direct the FCC to strengthen security requirements for commercial
undersea telecommunication cables landing in the United States beyond restrictions on certain
foreign equipment, such as establishing spatial requirements and requirements to avoid clustering
of cables, creating cable protection zones, diversifying routes, and installing redundant cable
lines—as the CSRIC has recommended.116
Congress could also direct agencies such as the FCC, DHS, DOD, and Department of State or
advisory bodies to work with industry to develop standards and criteria for improving commercial
undersea telecommunication cable security, voluntarily or through mandates. Congress may
encourage agencies and U.S. entities to engage in international organizations, such as ICPC.
Further, Congress may encourage or incentivize participation in the International
Telecommunications Union, an agency of the United Nations focused on improving global
communications, to promote U.S. recommendations for improving undersea telecommunication
cable security.
Addressing the Risk of Damage Through Commercial Activity
Congress may choose to address accidental damage by fishing vessels—a major cause of
undersea telecommunication cable faults. Congress could direct DHS to facilitate coordination
between industries (e.g., telecommunication, energy, fishing) and develop recommendations or
best practices to improve security and resiliency of undersea cables. Congress could direct the
FCC to seek public comment on CSRIC recommendations and adopt rules to strengthen the
security and resiliency of cables. Congress could direct the FCC or DHS to identify cables at the
highest risk of damage (e.g., in high traffic areas, clustered at certain landing points, single points
of failure) and develop damage mitigation polices and measures for those cables. Congress could
also impose steeper fines for damages.
Conclusion
Because the global commercial undersea telecommunication cable network carries about 95% of
intercontinental global internet traffic and 99% of transoceanic digital communications, it is

116 These recommendations apply to cables within U.S. jurisdiction. Commercial cables that extend from the United
States beyond U.S. territorial waters are not fully under the jurisdiction of the U.S. government. For cables that extend
beyond U.S. territorial waters, several international treaties dating from 1884 define the treatment of cables, establish a
state’s rights to lay cables in international waters, maintain cables, and impose punishment for damage to cables. While
the United States has not ratified the latest treaty governing cables, the United Nations Convention on the Law of the
Sea (UNCLOS), it has codified the terms of the treaty as they relate to undersea cables (47 U.S.C. Chapter 2). For a
discussion of the treaties governing international undersea telecommunication cables, see CSRIC, WG8 Spatial
Separation Report, December 2014, pp. 42-46.
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essential infrastructure for information exchange and commerce. In addition to natural threats to
this infrastructure, there are inadvertent threats from human activity such as commercial fishing
and shipping as well as deliberate damage and disruption of service by a variety of threat actors.
Congress may examine the U.S. approach to commercial undersea telecommunication cable
security and consider policies to strengthen it. It may conclude that commercial undersea
telecommunication cable security should remain primarily the responsibility of private sector
cable owners and consider policies that incentivize cable owners to increase their security
posture. Alternatively, Congress may determine that, due to the centrality of the global
commercial undersea telecommunication cable network to information exchange and commerce,
it should consider policies that strengthen coordination and cooperation among federal agencies
and with the private sector to ensure security of the cable network.

Author Information

Jill C. Gallagher

Analyst in Telecommunications Policy

Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
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