TL;DR: A fourth undersea cable fault has widened Vietnam's international internet bottleneck, with telecom operators VNPT and Viettel rerouting traffic and adding emergency capacity to keep the country's connection stable. For enterprises that depend on cloud services and cross-border data pipelines, the Vietnam submarine cable outage is a reminder that infrastructure resilience, not just data quality, decides whether critical systems stay online.
On August 25, 2026, the SJC2 submarine cable, which connects Vietnam to other Asian countries, developed a fault at its S4 segment near Chung Hom Kok in Hong Kong, becoming the fourth international submarine cable link currently degraded and extending the Vietnam submarine cable outage that has built up since February 2026 (Source: VnExpress, August 27, 2026).
Two other cables, AAG (Asia-America Gateway) and IA (Intra-Asia), are also faulted and are not expected to begin repairs until early September, while the AAE-1 cable has been down at its S1.H2 segment since February. For enterprises running cloud workloads and cross-border data pipelines out of Vietnam, four simultaneous cable faults is an unusually severe disruption.

What Caused the Vietnam Submarine Cable Outage This Week?
Vietnam currently relies on six international submarine cables: AAG, IA, AAE-1, APG, ADC, and SJC2, with ADC and SJC2 the two newest additions to the network. Internet users in Vietnam reach the rest of the world through a mix of submarine cables, land cables, and satellite internet, but submarine cables carry the large majority of that traffic, so the current Vietnam submarine cable outage has measurably reduced the country's total international bandwidth.
Cable faults are not new: Vietnam's international submarine cable system has logged roughly 40 incidents since 2022, an average of about 10 per year, and there have been earlier stretches when four of five active cables were degraded at once. What sets the current Vietnam submarine cable outage apart is the length of the AAE-1 repair, unresolved since February, compounding with three newer faults in the same window.
How Are Telecoms Responding to the Vietnam Submarine Cable Outage?
VNPT (Vietnam Posts and Telecommunications Group), one of Vietnam's largest telecom operators, said it began rebalancing traffic toward its remaining working routes as soon as the fault appeared, describing the situation as force majeure tied to the Vietnam submarine cable outage that is affecting every internet service provider in the country. International services such as web browsing, video, and overseas game servers may run slower during peak hours, though domestic connectivity remains stable thanks to backup infrastructure.
Viettel, Vietnam's military-run telecom group, said it is absorbing impact from both the IA and AAE-1 faults, with AAE-1 a total loss of connection for its network. On the evening of August 26, Viettel added 800 Gbps of international capacity via the IA route toward Hong Kong, and is fast-tracking another 300 Gbps via the APG cable, due by August 31. The company is also shifting some traffic onto a land route through Laos to Singapore, adding 1.5 Tbps of capacity there before the same deadline.
Why Does the Vietnam Submarine Cable Outage Matter for Data Resilience?
If needed, Viettel says its own ADC submarine cable, launched in 2025 and linking Vietnam to the three largest transit hubs in Asia, Hong Kong, Singapore, and Japan, can be upgraded to carry up to 50 Tbps and absorb the country's entire international internet load on its own. That kind of built-in redundancy is exactly what limits the damage from a Vietnam submarine cable outage; cable repairs themselves typically take months, sometimes up to a year, due to permitting, weather, and specialized repair-ship availability.
To reduce dependence on submarine routes, Vietnam brought its first international land cable, VSTN, into service in 2025 and approved a pilot for satellite internet the same year, with Starlink becoming the first approved provider in mid-August 2026. For enterprises, the lesson of the current Vietnam submarine cable outage is the same one DataCore has emphasized around Vietnam's post-quantum cryptography roadmap: infrastructure resilience has to be planned years in advance, not patched together after an incident.
Frequently Asked Questions
What is causing the Vietnam submarine cable outage?
Four international submarine cables serving Vietnam, SJC2, AAE-1, AAG, and IA, are simultaneously faulted as of August 27, 2026, with SJC2 the most recent to fail, on August 25, at its Hong Kong segment.
How are Vietnamese telecoms responding to the cable faults?
VNPT is rebalancing traffic across its remaining routes, while Viettel has added 800 Gbps via the IA cable and is adding 300 Gbps via APG and 1.5 Tbps via a Laos-Singapore land route, all by August 31, 2026.
How often do submarine cable faults happen in Vietnam?
Vietnam's international submarine cable system has recorded about 40 incidents since 2022, an average of roughly 10 per year, and has experienced comparable multi-cable outages before.
What backup options does Vietnam have during a submarine cable outage?
Vietnam can reroute traffic through its VSTN land cable, launched in 2025, the high-capacity ADC submarine cable owned by Viettel, and a new satellite internet pilot led by Starlink that began in mid-August 2026.
As the Vietnam submarine cable outage shows, enterprises that depend on cross-border connectivity need infrastructure partners with verified redundancy, not just fast connections on a good day. DataCore's Services hub gives technology and operations teams a single, verified view of the Vietnamese companies and infrastructure providers behind the country's digital backbone. Source: VnExpress, August 27, 2026.






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