Taiwan Takes Stronger Action Against Ships Threatening Its Submarine Cables

When a submarine cable between Taiwan and the Penghu archipelago was severed in the early hours of February 25, Taiwan’s Coast Guard acted swiftly, detaining a cargo ship at the site of the cable break.

Taiwan had been on high alert due to a series of recent incidents involving damaged submarine cables. The ships suspected of causing these disruptions shared several characteristics: they were old, rusted vessels sailing under flags of convenience, with ownership structures tracing back to China or Hong Kong. Moreover, they had been loitering near the cables for days or even weeks.

In the most recent case, the Coast Guard had already taken notice of the freighter Hong Tai 168, which had spent three days in Taiwanese waters off the southern port city of Tainan. The vessel was just half a nautical mile from a data cable connecting Taiwan to the Penghu archipelago in the Taiwan Strait. Despite repeated Coast Guard radio instructions to leave the area, the crew ignored the warnings.

After Chunghwa Telecom reported the cable break, the Coast Guard intervened. Chunghwa Telecom, Taiwan’s largest telecommunications provider and operator of the Penghu cable, is partly state-owned. Due to rough sea conditions, coast guard officers were unable to board the ship at sea, so they escorted it to the port of Anping in Tainan. The eight crew members, all Chinese nationals, were detained.

The Coast Guard stated that it remains unclear whether the cable break was intentional or accidental. However, authorities are investigating the possibility that it was a Chinese grey-zone operation. A local court found substantial evidence of a crime and ordered the captain’s arrest. According to local media, the captain denies intentionally cutting the cable.

There are several indications that sabotage may have been involved. The Coast Guard reported that the ship is Chinese-owned but sails under the flag of Togo—a known flag of convenience. Additionally, it transmitted a different name via AIS than the one displayed on its hull.

Taiwan Maintains a Blacklist of Suspicious Ships

Taiwan’s decisive action in this case contrasts with a similar incident earlier in the year. On January 3, Chunghwa Telecom reported a submarine cable severed off the northern port of Keelung. When the Coast Guard arrived, they encountered a cargo ship suspected of cutting the cable with its anchor. Due to rough seas, they were unable to board the ship. After a brief investigation via radio, they allowed the vessel—alternatively flying the flags of Cameroon and Tanzania—to leave Taiwanese waters. The case remains unresolved.

In response to such incidents, Taiwanese authorities have tightened rules of engagement for suspected cable threats. Cooperation has been strengthened between the Coast Guard, Navy, National Security Council, and Chunghwa Telecom.

One key measure is a blacklist of ships under heightened observation. Given the constant presence of countless vessels in the Taiwan Strait and near Taiwanese ports, identifying, inspecting, and expelling suspicious ships in time is a significant challenge.

The blacklist includes vessels with specific characteristics:

1. Flags of Convenience: Ships registered in Cameroon, Tanzania, Mongolia, Togo, and Sierra Leone are included. These flag states often fail to investigate or prosecute criminal activities by ship crews, despite this being their legal responsibility.
2. Ownership Links to China, Hong Kong, or Macau: Ship ownership is often obscured through complex, nested corporate structures, but Taiwan’s authorities focus on vessels with identifiable connections to these regions.

Currently, 52 ships are on the blacklist. According to the Financial Times, which reviewed the list, the Hong Tai 168 was included. While Taiwanese officials have not confirmed this, its presence on the list may have facilitated the Coast Guard’s rapid intervention.

While the Coast Guard leads in protecting submarine cables, Taiwan’s Navy can also be involved under the new rules of engagement. Defense Minister Wellington Koo announced in January that the Navy would assist the Coast Guard by providing surveillance capabilities when necessary. However, the Coast Guard remains the primary agency responsible, with naval involvement limited to situations requiring additional support.

By deploying the Coast Guard—a civilian organization—Taiwan signals that it views cable damage as a criminal act rather than an act of war. Under Taiwanese law, damaging submarine cables is a criminal offense. By holding back the Navy, Taiwan seeks to prevent escalation, as Beijing appears to be searching for pretexts to justify harsher actions.

In October, Admiral Tang Hua, Taiwan’s Navy commander, told The Economist that the PLA Navy is looking for “excuses” to impose a blockade: “It is trying to force Taiwan to make mistakes.” He added, “We restrain our guys, not to provoke or escalate.”

Taiwan Strengthens Backup Systems

Disruptions to the world’s 450 submarine cable systems are common. The International Cable Protection Committee reports that 150 to 200 cables are damaged globally each year, primarily due to fishing trawlers and dragging anchors.

Taiwan’s cables, however, appear to be damaged disproportionately often. Since the beginning of the year, there have been at least three reported incidents. Repairs are costly and time-consuming. For example, a data cable between Taiwan and Matsu was interrupted on January 15 due to aging infrastructure. The repair took 46 days, highlighting the logistical challenges involved.

However, Taiwan’s backup systems are improving. Two years ago, when both cables to Matsu failed, data traffic to the island group—just a few kilometers from the Chinese mainland—was severely disrupted. This time, a microwave connection successfully absorbed most of the data traffic. Similarly, backup systems ensured continued data transmission to Penghu.

If, however, the main cables connecting Taiwan to the global internet were severed, the consequences would be far more severe. Taiwan has 14 such connections, and microwave links function only over short distances with a clear line of sight. The data needs of Taiwan’s 23 million people and its internationally connected economy could only be met by a low-orbit satellite system.

The most advanced solution would be Starlink, but its owner, Elon Musk, has strong business ties to China. Musk has also publicly stated that he views Taiwan as part of China. Taiwan is to China what Hawaii is to the US, Musk said.

As a result, Taiwan is working to establish its own satellite system. The government has allocated nearly $9 billion to develop the national space industry, with the first Taiwanese satellite scheduled for launch into low Earth orbit by 2026. However, full deployment and the creation of a secure alternative to submarine cables will take years.

Until then, Taiwan has no choice but to closely monitor its undersea cables and take swift, decisive action against suspicious vessels. The stricter rules of engagement are a step in the right direction—not only do they impose a cost on China’s grey-zone operations, but they also expose Beijing’s activities to the global community.

A further step would be international cooperation, similar to how NATO countries collaborate to protect seabed infrastructure in the Baltic Sea. While Taiwan’s limited diplomatic ties present a challenge, they do not preclude all forms of cooperation with neighboring states. Coordination between coast guards is politically less sensitive than naval cooperation, making it a more feasible option.

Japan is the most obvious partner, given its highly capable coast guard. Many of the cable systems supplying Taiwan also connect to Japan, giving Tokyo a strong interest in ensuring their security. Taiwan and Japan’s coast guards already collaborate on fisheries management, and expanding this cooperation to include the protection of submarine cable systems is both logical and achievable.