Undersea cables: The new US-China frontline

Following the trade war, chip war and 5G competition, China-US strategic rivalry has extended from land to the seabed, with undersea cables becoming another frontier of great power competition.

Interviewed academics noted that China and the US may seem to be competing over communications infrastructure, but in essence the contest is for leadership in the digital order, along with the security, standards and market interests that underpin it, with the competition increasingly drifting towards bloc-based rivalry.

Four countries, 90% of global market

There are currently around 570 undersea cables worldwide, carrying 95% to 99% of international internet traffic and supporting more than US$10 trillion in financial transactions each day. These “data highways” laid across the seabed not only underpin global communications and the digital economy, but are also increasingly becoming a critical infrastructure where national security and geopolitics intersect.

The US Federal Communications Commission announced in early June that it plans to tighten the regulation of undersea cables, for the first time requiring operators of submarine line terminal equipment to apply for licences. The move is seen as an effort to further restrict Chinese companies’ participation in submarine infrastructure, while also creating a fast-track approval channel for trusted US technology firms.

As early as US President Donald Trump’s first term, the US introduced the “Clean Network” initiative, citing national security, data privacy and counterespionage concerns to tighten scrutiny of submarine communications infrastructure. Through legislation and diplomatic manoeuvring, it also moved to exclude Chinese companies from a number of key projects.

Meanwhile, China has leveraged HMN Tech and the Digital Silk Road initiative to remain involved in the construction of undersea cables and communications networks across Asia, Africa, the Middle East and Latin America. Offering relatively low-cost, end-to-end solutions, it has expanded its digital infrastructure footprint across the Global South.

For a long time, the global undersea cable construction market was dominated by the US’s SubCom, Japan’s NEC, and France’s Alcatel Submarine Networks. China’s Huawei Marine Networks entered the fray in 2008, but following US sanctions on Huawei in 2019, its submarine cable business was divested. Huawei Marine Networks was later renamed HMN Tech.

Ding Gang, a senior fellow with the Chongyang Institute for Financial Studies at Renmin University of China and a senior editor at the state-run People’s Daily, wrote in an article on his WeChat account that companies from these four countries together account for nearly 90% of the global submarine cable market. Among them, the US accounts for over 30%, while China’s share is around 15% and continues to rise.

From commercial infrastructure to strategic asset

As undersea cables evolve from commercial infrastructure into strategic assets, the nature of competition has shifted from market and technological rivalry to political considerations and security governance. An increasing number of projects now factor in geopolitical considerations when planning routes, selecting suppliers, and even determining landing sites.

For example the SeaMeWe-6 project, which connects Southeast Asia, the Middle East and Europe, Reuters reported in 2023 that, under US lobbying, the contract — initially intended to be awarded to a Chinese supplier — was ultimately transferred to the US’s SubCom. Some of the routes originally planned to land in Hong Kong were also altered or even cancelled.

Unlike the semiconductor industry, which is constrained by high technological barriers, competition in the undersea cable sector depends more on political, diplomatic and market access considerations.

Since China proposed the Digital Silk Road in 2017, it has consistently advanced the development of undersea cables, data centres and communications infrastructure, strengthening its global connectivity and technological influence. 

According to a 2025 report by the Industry and Planning Research Institute of the China Academy of Information and Communications Technology, HMN Tech has undertaken a total of 140 undersea cable projects, spanning more than 70 countries and regions. Among them, HMN Tech has led projects such as the PEACE cable system, which stretches across Asia, Africa and Europe, as well as the Asia-Africa-Europe-1, South East Asia-Middle East-Western Europe-5, and the South Atlantic Inter Link connecting Africa and South America. Together, these projects form part of China’s participation in the global undersea communications network.

For instance, the US, together with partners such as Japan, Australia and New Zealand, has in recent years strengthened its undersea cable presence in the second island chain and the South Pacific, in an effort to counter China’s growing influence in the region.

Su noted that behind undersea cables lies vast economic value, which is also a key reason for US-China competition. According to public estimates, the undersea cable hardware construction market — including cables, seabed engineering and landing stations — is expected to be worth around US$20 billion by 2026. With the expansion of artificial intelligence applications, it could grow to US$55 billion by 2034.

Dividing a borderless network

Wang Yiwei, director of the Institute of International Affairs at Renmin University of China, argued that despite geopolitical tensions, the global internet remains — in both physical and logical terms — a single entity that is difficult to split into opposing blocs. He said, “Once you enter a country, there is digital sovereignty, content sovereignty or infrastructure sovereignty, but globally it is still one network. The internet has no borders.”

Wang thinks that China’s “fast, high-quality and low-cost” undersea cable construction not only challenges the longstanding dominance of Western firms in the market, but also threatens their commercial interests. The US’s restrictions on Chinese companies on national security grounds are likewise driven in part by a desire to preserve its competitive advantage.

He also noted that, following the Edward Snowden revelations, the US government was accused of using the PRISM surveillance programme to collect a wide range of data, including emails, chat records and browsing activity. As a result, many countries may have lost trust in the US and sought to bypass it in undersea infrastructure.

As undersea cables take on an increasingly strategic character, great power competition is no longer limited to who lays and operates these “data highways”, but also extends to who can protect them — and who might sever them — in the event of a crisis.

Rising tensions in the Middle East have fuelled concerns that repair vessels for undersea cables may be unable to pass through the Strait of Hormuz, delaying repair and upgrade work. In recent years, cable breaks in the Baltic Sea, the North Sea and around the Taiwan Strait have heightened fears among countries that undersea cables could become a new target in grey-zone conflicts.

Seventeen countries jointly issued the “Guiding Principles for Underwater Infrastructure Defence Exchanges” at the Shangri-La Dialogue held in Singapore at the end of May, with the aim of strengthening the security of critical underwater infrastructure. However, both China and the US did not take part, and both sides have yet to establish any bilateral communication mechanism to address undersea cable issues.

In addition, the US, the UK and Australia have also announced that, under the AUKUS security partnership framework, they will jointly develop uncrewed undersea vehicle technology to protect undersea cables and enhance defence capabilities.

Su thinks that the latest move by the US, the UK and Australia is widely viewed as targeting Beijing, while the absence of both Washington and Beijing from the guidelines suggests that both may be seeking to preserve strategic space for future undersea intelligence operations.

From construction and operation to protection and potential disruption, undersea infrastructure has evolved from a commercial network component into a strategic asset in great power competition. The global internet remains a single network, but geopolitics is increasingly shaping how it is connected, who controls it, and under what rules it operates.

For China and the US, the contest is not only over fibre-optic cables laid on the seabed, but also over control of the digital-era infrastructure and the broader international order.

This article was first published in Lianhe Zaobao as “中美竞争延伸至海床“数据高速公路””.

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