Strategic importance of, and dependence on,
undersea cables
November 2019
About this paper
This paper is a collaborative view of the NATO CCDCOE Strategy and Law Branch researchers
highlighting the strategic importance of undersea cables in cyber security and the dependence of
states on their functioning. This is not a complete catalogue of states’ dependence on undersea
cables for cyber security, neither are the issues presented in any particular order. While the authors
have made an effort to describe the dependence on undersea cables from a global perspective, it is
acknowledged that there may be national and regional differences.
The authors of this paper are independent researchers at the NATO CCDCOE; they do not represent
NATO, nor does this paper reflect NATO’s position. The aim of the paper is solely to make member
states and partnering countries reflect on the transmission of data via undersea cables and where
necessary, strengthen their security efforts in this area.
1. What are undersea cables and why
do we depend on them?
a. More than 97% of all internet traffic is
transmitted via undersea cables.
Today,
practically everyone is reliant on the internet
on a daily basis. We are connected via the
internet, both personally and as part of
society. Modern societies put more and more
emphasis on cloud computing – the practice
of using a network of remote servers hosted
on the internet to store, manage and process
data, rather than a local server or a personal
computer. The “cloud” is therefore in reality
nothing but servers, which may be on another
continent but linked to you via cables.
b. Even if drastically improved, transmitting
data via satellite would only be able to
cope with a fraction of our requirements.
Transmission of data via cables is both
cheaper and many times faster than via
satellite and the technological possibilities
therefore dictate the use of cables for internet
connectivity. On land, this poses relatively few
complications as the cables are protected by
their owners and national jurisdiction.
Protection at sea, however, both physical and
legal, is more difficult.
c. When connecting continents or land
divided by sea, undersea or submarine
cables are installed on the ocean floor.
Without the functioning of these cables,
connectivity would be lost between nations or
territories divided by sea.
Just as we are reliant on the electrical power
grid for the functioning of modern society, we
have become reliant on internet connectivity.
The cables providing this connectivity are
therefore part of our critical infrastructure, and
must be protected as such to safeguard the
sovereignty of the data needed for a modern
society to function.
d. Modern undersea cables use fibre-optic
technology to pass data literally at the
speed of light. Even though the cables may
be strengthened near the shore, the average
diameter of a fibre-optic cable is not much
greater than that of a garden hose.
The diagram below (Fig.1) illustrates the
cable composition.
Fig. 1. Diagram of an undersea cable
(www.telegeography.com).
e. As the central nervous system of the
global internet, undersea cables are
strategically important and as such are
part of the critical infrastructure of
societies. Most countries have identified their
critical infrastructure and made plans for its
protection. However, as undersea cables
joining countries and continents must pass
through international waters, they cannot
solely be protected by national legislation,
