For half an hour on Thursday, mobile phones across Taipei and six other Taiwanese cities and counties slowed to a crawl. Streaming stalled, video calls froze and social media apps struggled to load a single image. It was not a network fault, but a deliberate test.
The slowdown was part of the last phase of Taiwan's annual Han Kuang exercises, military drills that began the previous week and aim to model a response to a possible Chinese military invasion. This year, for the first time, authorities added a simulated communications blackout to the programme. Telecommunications operators throttled mobile web traffic down to roughly 256 kilobits per second, a speed that made it difficult to exchange anything beyond simple text messages.
Sirens, shelters and a slow internet
The drill began with the routine familiar from previous years of Taiwan's civil defence exercises. As The Guardian reported, sirens sound across the capital and police direct people off the streets and into shelters and metro stations. This year, however, the disruption did not stop at street level.
Chen Hui-xuan, an 18-year-old who tried to use her phone on the metro during the drill, told The Guardian: "TikTok wouldn't open at all. Facebook worked, but it was really slow, and messages on Instagram took around 30 seconds to send."
President Lai Ching-te acknowledged the inconvenience caused to ordinary citizens. "We ask for your understanding and support, as this is a necessary drill," he said, according to reporting carried by NPR. Authorities had rolled out the throttling in stages across three regions of the island in the days before the Taipei drill, testing the approach first in Taichung on 10 August.
Why the undersea cables matter
The exercise reflects mounting concern in Taipei about the physical infrastructure that keeps the island connected to the world. Taiwan's submarine cable network comprises 16 international cables and 10 domestic ones, which its government has called an "irreplaceable digital lifeline".
Several of these cables have been damaged in recent years in episodes involving Chinese or China-linked vessels. Taiwan's coast guard has described the pattern as a "grey zone" strategy intended to drain the island's resources without crossing the threshold into open war. In 2025, a Chinese ship's captain was convicted of deliberately cutting a cable linking Taiwan's main island to an outlying territory, according to the same Guardian report.
“"We ask for your understanding and support, as this is a necessary drill." — President Lai Ching-te”
Researchers at the Global Taiwan Institute, a Washington-based think tank, have argued that undersea cable sabotage is no less dangerous than warplanes or missile drills, describing it as a frontline in a wider contest over digital infrastructure, a characterisation Beijing rejects.
A wider test of resilience
The internet slowdown was one strand of a broader update to the Han Kuang exercises this year. According to the Washington Examiner, it was the first time the military drills were paired with internet restriction exercises, staggered across three regions of the island, and reconnaissance drones were also incorporated for the first time. A Taiwanese defence official told the outlet the measures were meant to strengthen the island's own defence capabilities and resilience, while also contributing to the broader peace and stability of the Taiwan Strait and the Indo-Pacific.
For readers across Europe, the exercise carries echoes of concerns already voiced in the Baltic states and the North Sea, where NATO members have grown wary of damage to undersea data and energy cables linked to Russian-flagged vessels. Taiwan's drill suggests that democracies far apart geographically are reaching a similar conclusion: that cables on the seabed are now as strategically sensitive as borders on land.
Opinion within Taiwan remains split over whether a single 30-minute slowdown can meaningfully prepare citizens and businesses for a genuine wartime disruption, with commentators quoted by regional outlets divided over the drill's practical value. Officials nonetheless appear intent on repeating and refining the exercise, treating a resilient internet connection as a matter of national defence rather than mere convenience.
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