JAKO: A Planned Submarine Cable Connecting South Korea and Japan
The JAKO submarine cable is a planned telecommunications system designed to link
Busan in South Korea with
Fukuoka in Japan. With a total length of 260 kilometers, JAKO is expected to provide a direct and low-latency connection between these two important hubs in Northeast Asia. The cable is jointly owned by Amazon Web Services, Arteria, Dreamline, and Microsoft, all of whom are major players in the technology and telecommunications industries. Its ready-for-service (RFS) date is recorded as 2027 in GeoCables' database, but as of now, the cable is not yet operational.
What sets JAKO apart is its potential to enhance connectivity between South Korea and Japan, two countries with highly developed digital economies and dense submarine cable networks. However, several technical details about the cable remain undisclosed, including its design capacity, number of fiber pairs, supplier, and specific technological features. These unknowns make it difficult to assess its full impact on the corridor until further information becomes publicly available.
Quick facts
| Cable name | JAKO |
| Length | 260 km |
| Ready-for-service year | 2027 (GeoCables database) |
| Owners | Amazon Web Services, Arteria, Dreamline, Microsoft |
| Status | Planned - Not yet in operation |
| Design capacity | Not disclosed |
| Fiber pairs | Not disclosed |
| Supplier | Not disclosed |
| Landing points | Busan (South Korea), Fukuoka (Japan) |
🗺 Show JAKO on the interactive cable map
Route
The JAKO cable will connect Busan, South Korea, to Fukuoka, Japan. Busan is a major port city and a critical hub for international submarine cables, hosting several systems including
APCN-2,
Asia Pacific Gateway (APG), and New Cross Pacific (NCP). Fukuoka, located on Japan's Kyushu Island, is another important landing site, already connected by cables such as the
Korea-Japan Cable Network (KJCN) and the
I-AM Cable. This corridor is well-established, with multiple cables already serving the route between South Korea and Japan.
Why it was built and what it carries
The JAKO cable is being developed to provide additional capacity and redundancy in the heavily trafficked South Korea-Japan corridor. Both countries are leaders in technology adoption and data consumption, and their economies rely heavily on strong international connectivity. Given the involvement of major cloud providers like Amazon Web Services and Microsoft, JAKO is likely intended to support high-bandwidth enterprise applications, cloud services, and data center interconnectivity. However, specific details about its design capacity and technology have not been disclosed, leaving the full scope of its capabilities uncertain.
History: what can be established
GeoCables records JAKO's ready-for-service year as 2027, but as the cable is still in the planning phase, there is no operational history to analyze. If industry sources suggest a different RFS year, this could be due to delays in permitting, construction, or other logistical challenges common in submarine cable projects. For now, 2027 remains the most authoritative estimate available.
Capacity and technology
Publicly available information does not confirm JAKO's design capacity or the number of fiber pairs it will contain. Without documentation from the owners or suppliers, it is impossible to state these specifications. Similarly, the cable's supplier and technological features remain undisclosed. This lack of transparency is not unusual for planned cables, as detailed specifications are often revealed closer to the deployment phase.
Latency: the physics
The theoretical one-way light propagation latency for JAKO's 260-kilometer wet segment is approximately 1.3 milliseconds, with a round-trip time (RTT) floor of 2.5 milliseconds. This calculation assumes optimal conditions and excludes latency contributions from terrestrial network segments, terminal equipment, and routing. Real-world latency measurements, such as those recorded by GeoCables' remote probes, show significantly higher RTTs due to these additional factors. For example, the measured Busan-to-Fukuoka RTT averages 19.2 milliseconds, far exceeding the theoretical floor. This discrepancy highlights the difference between cable physics and the broader internet path.
Redundancy: what happens if it breaks
In the event of a failure, traffic on the JAKO cable could be rerouted through alternative systems that land at both Busan and Fukuoka, such as the I-AM Cable or the Korea-Japan Cable Network (KJCN). Both cables are established in the same corridor and provide redundancy for regional connectivity. Submarine cable repairs typically involve specialized ships and can take weeks, depending on the nature of the fault and weather conditions. Given the high density of cables in this corridor, redundancy is well-supported.
Bottom line
- JAKO is a planned submarine cable connecting Busan, South Korea, and Fukuoka, Japan.
- Its ready-for-service year is recorded as 2027, but it is not yet operational.
- Key technical details, including design capacity and fiber pairs, have not been disclosed.
- Theoretical latency for the wet segment is approximately 2.5 milliseconds RTT, but real-world measurements are much higher.
- Redundancy in the corridor is provided by existing cables such as the I-AM Cable and Korea-Japan Cable Network (KJCN).