Taiwan will test mobile network throttling during its 2026 Urban Resilience Exercise, prompting cross-party scrutiny and warnings that digital resilience is vital to public safety and essential services.How the exercise will workDuring air defense drills in central Taiwan on Aug. 10 and northern Taiwan on Aug. 13, mobile internet speeds will be reduced for 30 minutes in designated exercise areas, according to an official notice.Both 4G and 5G mobile data services will be affected, while voice calls, text messages, disaster alerts and emergency communications — including the 110 police and 119 fire and ambulance hotlines — will remain operational.Defense Minister Koo Li-hsiung (顧立雄) said on July 20 that the drill would test the military’s command-and-control systems and backup communications under simulated network disruption conditions. Similar drills are expected to be expanded to other areas in the future, Koo added. An ROC Army unit conducts an urban defense exercise in Taiwan. (MNA) Cross-party attentionDemocratic Progressive Party (DPP) Legislator Chen Kuan-ting (陳冠廷), convener of the Legislative Yuan’s Foreign Affairs and National Defense Committee, said the exercise was important because a real attack could disrupt communications for an entire day rather than just 15 or 20 minutes.One of his greatest concerns, he said, was that the Chinese Communist Party (CCP) could launch a false-flag operation at the same time as the drill, potentially magnifying the disruption's impact.Chen urged the government to explain how the exercise could affect daily life. Authorities should also clearly explain the drill’s procedures and objectives before it begins, he added.Opposition Kuomintang (KMT) Legislator Ko Ju-chun (葛如鈞) said he supported disaster preparedness and urban resilience exercises but opposed the way the current drill was being conducted.Ko said the government had not adequately explained the exercise’s legal basis, testing objectives, benchmarks for success, selection of affected areas, risk assessment, list of critical services or termination mechanisms.He called for the exercise to be suspended until those concerns were addressed, arguing that the government should instead focus on disaster roaming services, low-Earth orbit satellites and backup communications for critical services.How throttling differs from an outageHu Kei-young (胡克勇), a consultant at the Asia-Pacific Security Studies Center, told TCN that mobile network disruption differs from a full network outage.Hu said network outages in Taiwan can be divided into three categories.The first is a loss of external connectivity, in which communications between Taiwan and overseas networks are disrupted, potentially preventing users from accessing foreign servers, email services or cloud platforms, he said.The second involves damage to local infrastructure, Hu indicated, such as cellular base stations, fiber-optic cables or power facilities, resulting in the complete loss of mobile and fixed-line broadband services in a specific area.The third is a communications platform failure, such as the breakdown of cloud servers or individual service platforms, which could render certain applications unavailable, he said. An ROC Army unit conducts a defensive mission drill at a Taipei Metro station. (MNA) By comparison, mobile network disruption does not usually cut off all communications services, Hu said. Network capacity may instead decline, data traffic may become congested or operators may deliberately restrict bandwidth.Users might remain connected to the internet, but at substantially reduced speeds, making data-intensive services difficult or impossible to use, he added.Hu said mobile network disruption could occur when cellular base stations lose power, undersea cables are damaged or network traffic exceeds available capacity.In response, the government or telecommunications providers could introduce tiered traffic-management to reserve limited bandwidth for conventional voice calls and text messages, he said.Widespread outage as a national security issueHu said the effects of a large-scale network outage in Taiwan would extend far beyond the loss of access to social media, potentially affecting finance, transportation, logistics, healthcare, disaster response and national security.A major outage could disable mobile payments, credit card transactions and online bank transfers, while cross-border transactions and import-export operations could also grind to a halt, he said.In such a scenario, metro and high-speed rail ticketing, navigation, online shopping and logistics deliveries could also be disrupted, Hu said.Remote monitoring and coordination of water, electricity, healthcare and emergency response systems could also be impaired, increasing risks to critical infrastructure.From a national security and disaster-response perspective, Hu said a widespread outage could also interfere with the transmission of air-raid warnings, disaster alerts and government emergency information, leaving Taiwan at risk of becoming an “internet island” cut off from the outside world.If communications remained unavailable for an extended period, the disruption could trigger cascading consequences, including social instability, the suspension of economic activity and the spread of misinformation and disinformation, Hu added.Submarine cablesHu highlighted the critical role of submarine cables in Taiwan’s external internet connectivity.Taiwan relies almost entirely on submarine cables for its international internet communications, he said. If all international cables were severed, cloud services, email, cross-border transactions and import-export operations could cease functioning.Even partial damage could substantially reduce available bandwidth, Hu said, comparing it to reducing a four-lane road to two lanes, increasing the risk of network congestion.According to Taiwan’s Ministry of Digital Affairs (MODA), the country currently has 15 international and 10 domestic undersea communications cables and relies heavily on them for international connectivity and communications with its outlying islands. People walk along a street in Taipei. (Shutterstock) Drills should reflect real-world conditionsHu said digital resilience has become essential to maintaining public safety and the normal functioning of society.However, an exercise announced in advance, including its timing, geographic scope and expected impact, would likely have limited value in raising public awareness of mobile network disruption, he said.An unannounced mobile network throttling drill might provide a more accurate assessment of the government’s actual response capabilities, including the effectiveness of backup systems and its ability to restore services, Hu said.Such an exercise, Hu said, could also reveal gaps between strategic objectives and real-world conditions, allowing the government to identify areas for improvement and formulate concrete follow-up measures.Hu stressed, however, that public understanding and support would remain crucial to the success of any such exercise.