Protecting Undersea Cables: Innovative Solutions to Safeguard American Security
The MOC
By
Mike Daum
February 27, 2025
On February 25, 2025, Taiwanese authorities detained a cargo ship crewed by Chinese nationals suspected of sabotaging an undersea cable connecting Taiwan to its Penghu Island stronghold in the Taiwan Strait. This is not the first and will probably not be the last time America’s adversaries sabotage critical undersea infrastructure.
As U.S. policymakers seek to secure critical infrastructure, they must build resiliency in the undersea cable networks that underpin America’s national security.
When assessing threats to digital networks, it is reasonable to first think of activities in the cyber and space domains. However, observers should remember that undersea cables are the digital backbone of modern societies and are incredibly soft targets for bad actors. Digital networks cannot be considered secure if their underlying physical infrastructure is compromised.
Undersea cables transmit an estimated 97 percent of all intercontinental electronic communications, which support the global economy by enabling international communications and financial transactions worth trillions of dollars every day. Beyond these cables’ economic contribution, modern militaries heavily rely on this undersea network to support command, control, communication, computer, cyber, intelligence, surveillance, and reconnaissance (C5ISR) activities. In the event of a major conflict with China, Russia, or both, undersea cables will likely be one of the first targets attacked. As just one point of comparison, one of the first acts of the British Empire at the outbreak of World War One was to cut Germany’s undersea telegraph cables to the wider world.
But as seen recently, these adversaries are not waiting for a war to break out to target this infrastructure.
The suspected sabotaging of Taiwan’s undersea cables is not the first example of China targeting critical undersea infrastructure. This recent act of sabotage is already the second incident this year following a Chinese vessel damaging undersea cables connecting Taiwan, Japan, South Korea and the United States. The last major related incident in the region occurred two years ago, when Chinese vessels severed undersea cables connecting the Matsu islands from Taiwan proper.
Furthermore, China has not limited its malign activities to the Pacific theater. Also in 2023, a Chinese vessel damaged gas and telecommunication cables in the Baltic sea. Similarly, vessels described as “part of Russia’s shadow fleet” damaged several cables in this same “NATO Lake” in late 2024.
While natural hazards are known to threaten undersea infrastructure, the increasing risk of sabotage posed by America’s adversaries cannot be ignored.
According to the Office of the Director of National Intelligence, Russia maintains its ability to target critical infrastructure, including underwater cables and is “particularly focused” on increasing its capability to “damage infrastructure during a crisis”. To date, much of the attention regarding undersea sabotage has justifiably focused on Russia, but China’s growing military and commercial fleets pose significant threats to American and allied undersea infrastructure.
U.S officials recently warned that Chinese vessels are conducting espionage operations on undersea cables owned and operated by American companies to identify U.S. military communication links. These surveillance activities are likely meant to assess vulnerabilities in the U.S. military’s critical infrastructure to potentially dismantle or significantly disrupt America’s ability to respond to a crisis and capitalize on the U.S. military’s C5ISR advantages in a kinetic conflict.
The People’s Liberation Army’s (PLA) modern warfare doctrine, known as “multidomain precision warfare”, seeks to exploit vulnerabilities in the technological and communications networks supporting American military forces. By doing so, Beijing and Moscow believe they can level the playing field for their “good enough” military capabilities against exquisite U.S. platforms reliant on digital networks to connect sensors-to-shooters.
Although the threat to undersea sabotage has been exposed, a holistic solution is still lacking.
The Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency (CISA) is the lead for securing critical infrastructure. However, undersea cables have not been prioritized amongst the other assets DHS is responsible for. Even if CISA was directed to form a comprehensive strategy, there are numerous challenges associated with securing undersea infrastructure.
There are inherent difficulties involved in installing anything deep in the ocean. Seabed infrastructure faces immense pressure and continuous erosion. Although, the vast distances and varying maritime jurisdictions involved present even more complex challenges. International cooperation may have been overlooked as a future hurdle due to the assumption that interconnected economies and global institutions would be unifying factors in geopolitics. Unfortunately, recent events suggest otherwise.
In response to subsurface threats, NATO countries have deployed additional naval assets to the Baltic Sea to protect undersea cables. This operation may bolster cable security in Northern Europe, but the limited capacity of U.S. and allied fleets cannot safeguard the approximately 750,000 miles of undersea cables around the globe. Allocating more ships, whether through the Navy or the Coast Guard, is only a piecemeal approach to addressing the threat. Instead, policymakers should lean into American innovation to meet the challenge.
As some have noted in this publication, uncrewed underwater vessels (UUVs) “are radically transforming ocean transparency, from mapping the seafloor to detecting and shadowing commercial and military vessels,” which can “significantly reduce detection gaps”. Deploying UUVs to patrol along high-risk sections of undersea cable routes will significantly increase maritime domain awareness and make policing malign activities much more efficient.
Even with this increased domain awareness, deterring every sabotage incident is still unlikely. Repairing damaged cables is a complex, dangerous, and time-consuming process that can take months. If a conflict breaks out, these challenges will only be magnified. Leveraging innovative robotic technologies could be an efficient and effective solution to add resiliency to undersea infrastructure. While robotics have been involved in undersea cable repairs for years, additional resources should be invested in programs similar to those servicing ships and satellites.
Finally, the United States should leverage private capital and its allies to add redundancy to shared undersea infrastructure. Just as critical infrastructure and computer systems ashore are designed to avoid single point failures, having more cables in service will inherently boost network resiliency. Sabotage of a singular cable can cut off communication, but if that cable is one of many crisscrossing the ocean depths, information can be routed around a breach to maintain service. These cable projects are expensive, but leading U.S. companies have shown a willingness to invest in these projects and may be viable partners for the U.S. government. The United States should also invest more in allied initiatives like the Partnership for Cable Connectivity and Resilience and the South Pacific Connect projects announced in 2023.
The United States cannot eliminate its reliance on digital connectivity nor obviate the danger from the bad actors who threaten digital infrastructure. The best thing U.S. policymakers can do to safeguard its national security is build resiliency against undersea sabotage through our unique advantage— innovation.
Mike Daum is a national security professional based in Washington D.C. and a veteran of the 82nd Airborne Division. His work focuses on modern warfare, emerging threats, and the defense industrial base.
The views expressed in this piece are the sole opinions of the author and do not necessarily reflect those of the Center for Maritime Strategy or other institutions listed.
Center for Maritime Strategy
By Mike Daum
On February 25, 2025, Taiwanese authorities detained a cargo ship crewed by Chinese nationals suspected of sabotaging an undersea cable connecting Taiwan to its Penghu Island stronghold in the Taiwan Strait. This is not the first and will probably not be the last time America’s adversaries sabotage critical undersea infrastructure.
As U.S. policymakers seek to secure critical infrastructure, they must build resiliency in the undersea cable networks that underpin America’s national security.
When assessing threats to digital networks, it is reasonable to first think of activities in the cyber and space domains. However, observers should remember that undersea cables are the digital backbone of modern societies and are incredibly soft targets for bad actors. Digital networks cannot be considered secure if their underlying physical infrastructure is compromised.
Undersea cables transmit an estimated 97 percent of all intercontinental electronic communications, which support the global economy by enabling international communications and financial transactions worth trillions of dollars every day. Beyond these cables’ economic contribution, modern militaries heavily rely on this undersea network to support command, control, communication, computer, cyber, intelligence, surveillance, and reconnaissance (C5ISR) activities. In the event of a major conflict with China, Russia, or both, undersea cables will likely be one of the first targets attacked. As just one point of comparison, one of the first acts of the British Empire at the outbreak of World War One was to cut Germany’s undersea telegraph cables to the wider world.
But as seen recently, these adversaries are not waiting for a war to break out to target this infrastructure.
The suspected sabotaging of Taiwan’s undersea cables is not the first example of China targeting critical undersea infrastructure. This recent act of sabotage is already the second incident this year following a Chinese vessel damaging undersea cables connecting Taiwan, Japan, South Korea and the United States. The last major related incident in the region occurred two years ago, when Chinese vessels severed undersea cables connecting the Matsu islands from Taiwan proper.
Furthermore, China has not limited its malign activities to the Pacific theater. Also in 2023, a Chinese vessel damaged gas and telecommunication cables in the Baltic sea. Similarly, vessels described as “part of Russia’s shadow fleet” damaged several cables in this same “NATO Lake” in late 2024.
While natural hazards are known to threaten undersea infrastructure, the increasing risk of sabotage posed by America’s adversaries cannot be ignored.
According to the Office of the Director of National Intelligence, Russia maintains its ability to target critical infrastructure, including underwater cables and is “particularly focused” on increasing its capability to “damage infrastructure during a crisis”. To date, much of the attention regarding undersea sabotage has justifiably focused on Russia, but China’s growing military and commercial fleets pose significant threats to American and allied undersea infrastructure.
U.S officials recently warned that Chinese vessels are conducting espionage operations on undersea cables owned and operated by American companies to identify U.S. military communication links. These surveillance activities are likely meant to assess vulnerabilities in the U.S. military’s critical infrastructure to potentially dismantle or significantly disrupt America’s ability to respond to a crisis and capitalize on the U.S. military’s C5ISR advantages in a kinetic conflict.
The People’s Liberation Army’s (PLA) modern warfare doctrine, known as “multidomain precision warfare”, seeks to exploit vulnerabilities in the technological and communications networks supporting American military forces. By doing so, Beijing and Moscow believe they can level the playing field for their “good enough” military capabilities against exquisite U.S. platforms reliant on digital networks to connect sensors-to-shooters.
Although the threat to undersea sabotage has been exposed, a holistic solution is still lacking.
The Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency (CISA) is the lead for securing critical infrastructure. However, undersea cables have not been prioritized amongst the other assets DHS is responsible for. Even if CISA was directed to form a comprehensive strategy, there are numerous challenges associated with securing undersea infrastructure.
There are inherent difficulties involved in installing anything deep in the ocean. Seabed infrastructure faces immense pressure and continuous erosion. Although, the vast distances and varying maritime jurisdictions involved present even more complex challenges. International cooperation may have been overlooked as a future hurdle due to the assumption that interconnected economies and global institutions would be unifying factors in geopolitics. Unfortunately, recent events suggest otherwise.
In response to subsurface threats, NATO countries have deployed additional naval assets to the Baltic Sea to protect undersea cables. This operation may bolster cable security in Northern Europe, but the limited capacity of U.S. and allied fleets cannot safeguard the approximately 750,000 miles of undersea cables around the globe. Allocating more ships, whether through the Navy or the Coast Guard, is only a piecemeal approach to addressing the threat. Instead, policymakers should lean into American innovation to meet the challenge.
As some have noted in this publication, uncrewed underwater vessels (UUVs) “are radically transforming ocean transparency, from mapping the seafloor to detecting and shadowing commercial and military vessels,” which can “significantly reduce detection gaps”. Deploying UUVs to patrol along high-risk sections of undersea cable routes will significantly increase maritime domain awareness and make policing malign activities much more efficient.
Even with this increased domain awareness, deterring every sabotage incident is still unlikely. Repairing damaged cables is a complex, dangerous, and time-consuming process that can take months. If a conflict breaks out, these challenges will only be magnified. Leveraging innovative robotic technologies could be an efficient and effective solution to add resiliency to undersea infrastructure. While robotics have been involved in undersea cable repairs for years, additional resources should be invested in programs similar to those servicing ships and satellites.
Finally, the United States should leverage private capital and its allies to add redundancy to shared undersea infrastructure. Just as critical infrastructure and computer systems ashore are designed to avoid single point failures, having more cables in service will inherently boost network resiliency. Sabotage of a singular cable can cut off communication, but if that cable is one of many crisscrossing the ocean depths, information can be routed around a breach to maintain service. These cable projects are expensive, but leading U.S. companies have shown a willingness to invest in these projects and may be viable partners for the U.S. government. The United States should also invest more in allied initiatives like the Partnership for Cable Connectivity and Resilience and the South Pacific Connect projects announced in 2023.
The United States cannot eliminate its reliance on digital connectivity nor obviate the danger from the bad actors who threaten digital infrastructure. The best thing U.S. policymakers can do to safeguard its national security is build resiliency against undersea sabotage through our unique advantage— innovation.
Mike Daum is a national security professional based in Washington D.C. and a veteran of the 82nd Airborne Division. His work focuses on modern warfare, emerging threats, and the defense industrial base.
The views expressed in this piece are the sole opinions of the author and do not necessarily reflect those of the Center for Maritime Strategy or other institutions listed.