Cable wars: what to do about deepening conflict beneath the seas
On the day before Christmas in 2024, a Russian shadow-fleet oil tanker dragged its anchor a hundred miles across the Baltic seabed, damaging internet cables and the Finland-to-Estonia Estlink-2 power line.
The month before, the Chinese bulk carrier Yi Peng 3 did virtually the same thing, rupturing Baltic Sea internet cables.
In January 2025, this pattern was repeated north-east of Taiwan, where a Cameroon-registered Chinese vessel (Shunxing-39) damaged the Trans-PacificExpress Cable, which connects to South Korea, Japan and the United States.
Accidents at sea do happen. Sharks, porpoises and occasionally careless seafarers have for years disrupted communications cables on the seabed. Yet in recent years, and even in recent months, ostensibly “accidental” disruptions of undersea cables have abruptly escalated, not just around Taiwan, but in the Baltic, the Red Sea, and elsewhere as well.
What is provoking this rash of undersea conflict, and what does it portend more generally for international affairs?
The ultimate driver of cable wars, in the view of most experts, is the Information Revolution. As that fateful juggernaut proceeds, the internet increasingly shapes virtually every aspect of our lives. And 95 percent of internet traffic flows beneath the sea, mostly beyond nation-state borders, fueling both a rash of cable construction and the geopolitically driven tensions noted above.
Internet traffic flows beneath the sea for a variety of reasons. Most importantly, seaborne transmission is markedly cheaper and more efficient than through space – the principal alternative – since satellite hardware is more expensive to produce than fiber-optic cable.
Across international waters, through which the vast proportion of the internet flows, cable traffic also faces only minimal regulation, allowing operators enhanced flexibility in responding to changing demand patterns as technology evolves. Seaborne traffic is thus ideally suited to the rapidly evolving world of transnational service trade.
The information arteries that transmit the vast bulk of internet communications across the globe at the speed of light are around 400 major undersea cables stretching for a million miles in all, mainly across the Atlantic and Pacific Oceans from the United States to Europe and Northeast Asia, lying largely in international waters.
Lower capacity extensions connect Europe and Asia through the Indian Ocean, with still less imposing connectors linking in Latin America, Africa, and other parts of the world. Virtually all of this intricate network lies beneath the sea, with several of the most rapidly expanding portions being built in areas of severe US-China geopolitical competition.
Undersea cable traffic is thus at once increasingly vital economically, to advanced societies, and highly vulnerable to disruption. The economic (and geopolitical) importance triggers deepening competition among the top global players – particularly the United States and China. And the vulnerability attracts spoilers intent on asymmetrically challenging the dominant players – particularly Russia and a potpourri of global terrorists.
Over the past decade, “cable wars” have markedly accelerated, as geopolitics has entered the equation, for five basic reasons. One primary driver has been China’s rapidly expanding cable network, focused in the Pacific and developing nations stretching westward across the Indian Ocean to Europe and Africa.
Chinese cable construction has been heavily subsidized and has been focused on linking developing nations with under-developed information societies that are of strategic interest directly to China.
A second driver of cable wars has been similarly geostrategic – an American response to Chinese expansion across the Indo-Pacific, using both legal and physical tools. An opening shot was the US objection to a Chinese-inspired trans-Pacific cable from the US to Hong Kong, which American regulators rejected in 2024.
The US, in cooperation with Japan, then inspired an alternate trans-Pacific cable linking the US to Japan, South Korea, Taiwan, the Philippines and Singapore, via Palau.
The US also catalyzed the Sea-We-6 Indian Ocean cable from Singapore westward, in competition with China’s Peace cable from Gwadar in Pakistan through the Red Sea and the Mediterranean to Marseilles.
Thus, as the US marshaled diplomatic tools to prevent the construction of Chinese cables it also re-entered the cable-laying game, inspired by geopolitical competition. In these and related projects, the US and China battled fiercely to connect East Asia to Europe and Arica, in configurations favorable to themselves.
Three additional drivers of the deepening Eurasian cable wars have flowed from geopolitical conflict in critical regions of the world.
Most dramatic, of course, has been the Ukraine war, provoked by Russia’s February 2022 attack on Ukraine. As that conflict has steadily escalated, with Russian bombardment intensifying – even as the West has supplied more advanced weaponry to the Ukrainians – the Russians have seemingly found asymmetric undersea warfare, involving frequent covert, deniable attacks on undersea cables, to be a low-cost yet high-impact form of response.
The accession of Sweden and Finland to NATO in 2023 and the fragile yet deepening Nordic infrastructural ties to the former Soviet Baltic republics have given the Russians special geopolitical incentives to target Baltic infrastructure.
Deepening regional conflict – provoked by the October 2023 Hamas attack on Israel and followed by Israel’s unremitting response across the Iranian “Axis of Resistance” – has also stimulated cable warfare in the Middle East.
The Red Sea has been a particularly vulnerable arena, and proximate target, with over 10 percent of global internet traffic flowing through Egypt. The Shiite Houthis of Yemen, commanding the Arabian shores of the Bab al-Mandab, have targeted maritime commerce from the Indian Ocean to Europe and also have threatened undersea cable lines, especially those linked to the US and Europe.
The third Eurasian flashpoint, where cable wars have already broken out and seem destined to intensify, is the Taiwan Strait. Similarly to the case with the Russians in the Baltic, hybrid warfare suits a short-term Chinese geopolitical objective: to deepen pressure on the Taiwanese regime without provoking a kinetic response from the United States.
In 2023 Chinese ships damaged two subsea internet cables connecting Matsu and Taiwan, leading to internet blackouts on Matsu. In January 2025, a similar incident occurred – just the latest in a series of around thirty gray-zone undersea-cable incidents against Taiwan since 2017.
Looking to the future, the sea lanes of the Indo-Pacific as well as those of the Arctic seem likely candidates for further escalation of cable wars, as I note in my newly published book Eurasian Maritime Geopolitics.
The Indo-Pacific is the primary theater of rivalry between the cable war principals, the United States and China, with ample flashpoints that could provoke confrontation.
The sea lanes between Suez and Shanghai provide a variety of flashpoints that are especially tempting to disruptors – because they involve less-developed infrastructure than exists among the G-7 nations, while geopolitical tensions are high and littoral nations are less equipped to handle disruptions.
Apart from Taiwan, chokepoints such as the Strait of Malacca, where piracy has been a traditional problem, and the vicinity of American bases such as Diego Garcia offer prospects for cable conflict over competitive infrastructure building, surveillance and cable interdiction.
The status of potential landing stations and information hubs in nations such as Sri Lanka will likely be issues of contention, as well, especially as a dearth of nearby bases makes US response to cable disruption difficult.
Even natural factors such as global warming will likely accelerate the ongoing cable war; the Arctic is becoming an area of deepening information infrastructure construction that could inspire cable conflict as well.
With the rise in prospects that cable conflict will impair national security, both the White House and the US Congress fortunately are beginning to see the dangers involved. The Undersea Cable Security and Protection Act (H.R.9766), proposed in September 2024, is an important start.
In addition to improving the protection of undersea telecommunications cables and associated landing stations in the United States, America needs to work with NATO and other allies to counter Chinese, Iranian and Russian overt and gray-zone efforts as well.
Kent Calder is Director of the Reischauer Center for East Asian Studies at Johns Hopkins University SAIS, former Special Advisor to the US Ambassador to Japan and the recent author of Eurasian Maritime Geopolitics (Brookings, 2025).
