Undersea Data Cables: The Unseen Threat to U.S. National Security
Every ChatGPT prompt, every AI-generated insight, every high-frequency stock market trade, and every classified military order sent across the world depends on infrastructure few ever think about: undersea data cables. These cables carry 99% of the world’s data traffic, yet they remain almost entirely unprotected, unregulated, and unmonitored. China’s rising influence in the undersea cable market poses three threats to U.S. national security: physical sabotage, market influence, and espionage.
The U.S. and its allies are highly active in the undersea cable industry, with the U.S.-based SubCom installing 21% of global cables and France’s ASN installing 41%. Private content providers like Google, Microsoft, Meta, and Amazon own or lease nearly 50% of global undersea bandwidth. Despite these advantages, China’s Digital Silk Road initiative (led by state-backed firms like HMN Tech and China Unicom) is aiming to capture 60% of the cable market. The $500M EMA cable that connects Beijing with emerging markets across Africa, Southeast Asia, and Latin America is just one example of this strategy—embedding China’s influence deep into the world’s critical digital infrastructure.
Despite the critical importance of data to emerging technologies like artificial intelligence and advanced computing or big data, data cables lack the protections found in other critical sectors, leaving them vulnerable to cyber threats, surveillance, and sabotage. The energy and healthcare sectors, for example, benefit from Information Sharing and Analysis Centers (ISACs) that enable real-time collaboration between industry, government, and other stakeholders to prevent adversarial exploitation. Without a coordinated security framework, undersea cables are an easy target for sabotage, especially in times of geopolitical tension.
If a conflict were to arise between the U.S. and China over Taiwan, these vulnerabilities could quickly become a battlefield. Beijing could sabotage undersea cables, disrupting vital data flows. China has already patented technology designed to sever cables, and multiple incidents suggest that Chinese vessels have intentionally damaged cables before. The threat is real enough for Taiwan to conduct war games that included internet blackouts caused by undersea cable disruptions. Other simulations have found that the consequences of cable-cutting would be catastrophic.
Even if physical infrastructure remains untouched, landing stations (where cables connect to domestic networks) remain highly vulnerable to cyberattacks and foreign manipulation. The Office of the Director of National Intelligence (ODNI) has classified cyberattacks, vandalism, and foreign influence over these sites as ‘high risk’ national security threats. A breach of cable landing stations would enable China to reroute and throttle data traffic, including for US-based services. If Chinese state-owned firms own or maintain these systems, they don’t even need to hack them—their access is already assumed. These capabilities could easily be used to ensure that Chinese cloud and AI platforms outperform US competitors in markets with Chinese-owned cables or landing stations that are compromised.
These security vulnerabilities are compounded by another major weakness: the lack of legal regulation. Unlike domestic wire networks, which are protected by the Fourth Amendment and the Foreign Intelligence Surveillance Act, international cables operate in a legal gray zone. Any nation with access to cable infrastructure, whether through ownership, maintenance, or covert operations, can intercept the data inside. Western countries have engaged in similar activities as well: Britain’s Tempora program in 2011 siphoned global internet traffic through domestic landing stations, and the U.S. Navy tapped Soviet cables in 1971 during Operation Ivy Bells. Today, government, military, and corporate data flows through shared cable infrastructure, and the presence of globalized servers makes that risk even more severe.
With no legal safeguards guarding infrastructure in international waters, the only true defense is securing the data inside. Encryption and localization are two methods to mitigate data tapping, with the former making data temporarily unreadable and the latter ensuring that data stays within a supervised area. These measures help, but encrypted data can still be intercepted and stored. China and Russia are likely stockpiling data for future decryption, mirroring the NSA’s leaked BULLRUN initiative. If encrypted data is harvested today and decrypted using quantum–computing later, it would be disastrous for US national security.
Without decisive policy action, China will continue exploiting weaknesses in global digital infrastructure to expand its global influence. First, Washington must expand the mandate of interagency task forces like Team Telecom, utilizing advanced engineering solutions and companies to conduct active monitoring and ensure the integrity of undersea data cables. Second, the U.S. should establish an ISAC specifically for undersea cables to enable real-time monitoring and intelligence sharing across the government. Finally, policymakers must invest in additional security mechanisms to protect and oversee digital corridors or ensure all data networks are governed by the U.S. and its partners. The priority isn’t securing trust in today’s cables — it is ensuring the long-term resilience of the systems that underpin global communication.
