Four of Vietnam’s subsea cables hit by simultaneous faults, disrupting international internet traffic

Vietnam is once again grappling with widespread subsea cable disruptions, as four of the six international fiber-optic systems serving the country have suffered faults at the same time. The simultaneous failures have triggered fresh connectivity outages for local operators and users, underscoring the persistent fragility of Vietnam’s international bandwidth infrastructure.

According to local news outlet VN Express, the affected systems include the SJC2 cable, which links Vietnam to other parts of Asia; the AAE-1 cable, which has experienced recurring issues since February; the Asia-America Gateway (AAG), connecting Southeast Asia with the United States; and the Intra Asia (IA) cable. The exact nature of the faults has not been disclosed, but the outages are significant enough to disrupt operations for major mobile network operators, including VNPT and Viettel, and impact roughly 30 percent of Vietnam’s international internet traffic.

The SJC2 cable is the latest to develop a problem, with a fault detected in its S4 segment near Chung Hom Kok, Hong Kong, last week. Repairs on the AAG and IA cables are expected to begin this month, according to VN Express, though no timeline has been provided for the other systems.

In response to the disruptions, Viettel has moved quickly to bolster capacity, adding 800Gbps of international connectivity via the IA cable on Wednesday, along with an additional 300Gbps through the Asia Pacific Gateway. These measures are intended to mitigate the impact on users while repairs are carried out.

The latest incident is not an isolated event. Vietnam’s subsea cable network has faced repeated failures in recent years. In 2024, three cables—IA, APG, and AAE-1—were all hit by outages, and a year earlier, all five cables connecting the nation at the time were down simultaneously. The recurring nature of these disruptions highlights ongoing challenges in maintaining reliable international connectivity for the country, which remains heavily dependent on a limited number of undersea routes.

The latest faults also raise broader concerns about the resilience of Southeast Asia’s subsea infrastructure, as demand for bandwidth continues to grow across the region. With repairs on some cables still pending and new faults emerging, Vietnam’s operators are likely to face continued pressure in the coming weeks to maintain service quality for both domestic users and international traffic.