In February 2025, Taiwan’s coast guard noticed something unusual in the Taiwan Strait. A Togolese-flagged cargo ship, the Hong Tai 58, had slowed near a submarine cable route connecting Taiwan to the Penghu Islands. Officers repeatedly attempted to contact the vessel over radio, but it did not respond. Shortly after the ship dropped anchor, engineers at Chunghwa Telecom detected a break in the No. 3 submarine communications cable. Taiwanese authorities later detained the ship and its Chinese crew, and a court eventually sentenced the captain to three years in prison for intentionally damaging the line.
China is increasingly exploiting the vulnerability of submarine cables as a gray-zone tactic against Taiwan. By damaging Taiwan’s submarine cables in ways that can appear to be maritime accidents, Beijing can degrade the island’s digital connectivity. That pressure can slow communications, disrupt economic activity, and expose weaknesses in Taiwan’s response systems without triggering open conflict.
This strategy works in part because most submarine cable breaks are treated as accidents: Globally, 150 to 200 cable faults occur each year, and about 70 to 80 percent result from accidental human activities, mainly fishing and ship anchors. But officials have begun to notice a pattern around Taiwan. The National Security Bureau has reported an average of seven to eight cable breaks annually in recent years, many involving Chinese-linked vessels. Against that backdrop, the Hong Tai 58 incident drew particular scrutiny, becoming Taiwan’s first successful prosecution involving submarine cable sabotage by a Chinese-crewed vessel.
Subsea cables carry more than 99 percent of global internet traffic, including financial transactions, cloud computing data, diplomatic communications, and military coordination. More than 500 operational cables stretch across 1.48 million kilometers of seabed. Taiwan relies on 24 of them — 14 international and 10 domestic — to remain connected to global markets and security partners, including the networks that link its critical semiconductor industry to customers around the world. When a cable fails, internet traffic is redirected through other cables in the network. Those lines must suddenly carry far more data than they were designed to handle, creating congestion — connections slow down and capacity becomes limited until the cable is repaired. Fixing a damaged cable can take four to five weeks — a specialized repair ship must travel to the site, haul the cable ends up from the seafloor, splice in a new section of fiber, and lay the line back down while working around weather and ship availability. Many of these vessels are based in Japan or Southeast Asia, which means Taiwan’s dependence on foreign ships leaves recovery timelines partly outside of its control.
For Taiwan, those delays are not just a technical problem. Chinese leaders have repeatedly stated their determination to bring the island under Beijing’s control. President Xi Jinping has stated that China “will never renounce the right to use force” over Taiwan and has described reunification as “a trend of the times” that is “unstoppable.” In a confrontation across the Taiwan Strait, disrupting Taiwan’s digital infrastructure could play directly into China’s strategy. Taiwan relies heavily on digital networks to share intelligence, coordinate military operations, and communicate with partners such as the United States and Japan. If those connections slowed or failed, it could be critical to Taiwan’s defense posture.
The economic risks are equally severe. Taiwanese companies collectively hold around a 68 percent share of global semiconductor production, and Taiwan Semiconductor Manufacturing Company alone produces about 90 percent of the world’s most advanced chips. Disrupting the digital infrastructure that supports this industry could interrupt production and exports almost immediately. Analysts estimate that a conflict involving Taiwan could cost the global economy more than $10 trillion in the first year, underscoring how deeply the island’s technology sector is tied to global supply chains.
These vulnerabilities are particularly salient because China is also expanding the technological capabilities needed to exploit them. In March 2025, the China Ship Scientific Research Center unveiled a deep-sea device capable of cutting armoured communications cables at depths of up to 4,000 meters, well beyond the reach of most commercial vessels. The tool is intended to work with China’s fleet of deep-sea submersibles. One of these vehicles, Fendouzhe (“Striver”), can dive to nearly 11,000 meters, making it one of the deepest-diving crewed submersibles in the world. China has also expanded the ships that support these missions. In 2024, the country launched the research vessel Tan Suo San Hao, an 800 million yuan ship capable of deploying multiple submersibles and underwater drones. Together, these technologies give Beijing an increasing ability to disrupt the seabed infrastructure that underpins global communications.
The vulnerability of undersea cables is not limited to Taiwan. Similar incidents in recent years suggest the world’s digital infrastructure is becoming an increasingly contested space. In late 2024, cables connecting Finland to Germany and Sweden to Lithuania were damaged within 24 hours of each other. A Chinese bulk carrier, the Yi Peng 3, was reported near both sites, raising fears of coordinated attacks in the Baltic Sea. A UK study found that eight out of 10 vessels suspected of cable sabotage were linked to China or Russia. China’s activities have begun to pose a serious threat to the international order.
If submarine cables are becoming a tool of pressure in the Taiwan Strait, governments need to start treating them as strategic infrastructure. Much of the network that carries global communications sits on the seabed with little monitoring and limited capacity to repair damage quickly. Taiwan and its partners should increase surveillance along major cable routes, using coast guard patrols and satellite tracking to monitor vessels operating near cable corridors and landing stations. Expanding the number of cable repair ships stationed in the Indo-Pacific would also shorten the time it currently takes to restore damaged lines. Over time, adding more cable routes and strengthening backup systems would make Taiwan’s network harder to disrupt.
Of course, these steps cannot prevent every cable break. But, they would make it far harder to use cable damage as a quiet form of coercion. Undersea cables carry the communications, financial transactions, and data flows that sustain both Taiwan’s security and the global economy. Leaving them exposed gives Beijing an opportunity to apply pressure without firing a shot.
The next Taiwan crisis may not begin with missiles. It may begin with an anchor.