Red Sea Cable Cuts Strain Global Internet, Azure Latency Rises

Microsoft issued an urgent alert on Saturday after multiple undersea fibre-optic cables in the Red Sea were discovered cut, triggering increased latency for Azure customers and underscoring how fragile the physical backbone of the global internet remains.

Overview​

The disruption — first detected in the early hours of September 6, 2025 (UTC) — affected several major subsea systems in the Red Sea corridor, with operators and internet-monitoring groups reporting damage near Jeddah, Saudi Arabia. Two high-profile systems cited in operator notices and cloud-provider status bulletins were SEA‑ME‑WE 4 (often abbreviated SMW4) and IMEWE (India–Middle East–Western Europe). Microsoft’s Azure monitoring pages warned customers that traffic traversing the Middle East between Asia and Europe may experience higher‑than‑normal latency, and engineers immediately began rerouting traffic through alternate, albeit longer, paths to preserve service continuity.
This episode re‑opened a now-familiar debate: modern internet resilience is only as strong as the handfuls of fibre pairs on the seafloor linking continents. When those fibres break, the consequences cascade into cloud performance, regional business continuity, financial markets and everyday consumer services.

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Background: why the Red Sea matters for global Internet traffic​

The Red Sea and adjacent chokepoints — principally the Bab al‑Mandeb strait and the Suez/Egypt land crossing — are a concentrated corridor for cables connecting Europe, Africa and Asia. Industry analysis and telecom research consistently show a large share of Europe–Asia capacity traverses this route, and estimates commonly cited in the telecom and policy communities put the corridor’s share of global data flows in the mid‑teens percentage range.

• The Red Sea corridor carries an outsized share of Europe–Asia capacity, often quoted at roughly 90% of Europe–Asia trunk capacity.
• Across a broader global view, analysts and policy studies have repeatedly estimated that cables transiting the Suez/Red Sea region account for something on the order of 15–17% of global internet traffic — a single regional chokepoint that, if disrupted, moves the needle for global performance and availability.

Those numbers explain why cuts in this region create outsized effects: traffic that ordinarily crosses via a short undersea path now must detour around alternative routes, increasing latency and fatiguing peering and backbone links not sized for sudden extra load.

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What happened: timeline and immediate effects​

Detection and initial alerts​

• Monitoring systems and a number of network operators reported fibre cuts on September 6, 2025, with trouble reported from around 05:45 UTC in the affected areas.
• Microsoft posted service‑health updates to Azure’s monitoring/status channel warning customers of higher latency on routes that typically traverse the Middle East, particularly for flows between Asia and Europe.

Systems named and region of the fault​

• The affected subsea systems named in operator and media updates included SEA‑ME‑WE 4 (SMW4) and IMEWE, among others identified in real‑time network observability feeds.
• The geographic locus of the cuts was reported close to Jeddah, Saudi Arabia, placing the incident squarely in the busy, shallow waters of the northern Red Sea.

Immediate operational impact​

• Azure customers reported increased latency and slowdowns, especially on cross‑region services and applications sensitive to round‑trip times (real‑time communications, streaming, some database replication).
• Internet performance monitors and national operators reported degraded service in countries that rely on the corridor for international connectivity — including parts of the Middle East, South Asia and routes to Europe.
• To limit service disruption, cloud and network engineers activated traffic redirection and rebalancing, moving flows onto longer, more circuitous routes and into peering arrangements that could absorb the load.

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How cloud providers responded: routing, resilience and recovery​

Cloud providers and backbone operators have layered defensive measures, and this event exercised those controls.

• Traffic rerouting and path diversity: Microsoft’s network engineering teams implemented alternative paths to bypass the damaged segments. Those detours preserved connectivity but increased latency because traffic traversed longer physical distances and often passed through more congested intermediate networks.
• Load balancing and peering optimisations: Operators tweaked peering policies and intra‑provider load balancing to redistribute traffic away from stressed links.
• Enhanced monitoring: Providers increased telemetry and customer notifications to track user experience and to coordinate fixes.
• Service status updates: Microsoft and other cloud operators used service‑status channels to inform customers that services remained online in most cases, while urging customers to expect elevated latency on specific routes.

By September 7, several providers reported that services were largely restored to normal from an availability perspective, though repair work on the physical cables remained the long‑lead activity and full restoration of normal routing would depend on successful subsea repairs and the rebalancing of global transit.

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Technical anatomy: why undersea cable cuts are hard to fix​

Repairing a subsea cable is fundamentally an oceanic engineering task, not a straightforward network patch:

• Inspection and identification: Repairs require specialist ships that locate the damage using undersea sensors and grappling equipment. In shallow, geopolitically sensitive waters this work is dangerous or impossible until security conditions are assured.
• Cable type and repeater spacing: Long haul cables include powered repeaters; a cut near a repeater can complicate repairs and power restoration.
• Permits and access: Repair vessels need coastal permissions, safe anchorage and coordination with local authorities; conflict zones can deny physical access.
• Schedule and logistics: Even in calm environments, repairs can take days to weeks. When ships must transit from remote depots, or when security escorts are required, timelines extend to weeks.

These constraints mean that routing work by cloud and network operators — short of physically restoring the fibre — is the primary mitigation in the first days and weeks after a cut.

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Why attribution matters — and why it’s difficult​

When subsea cables are severed, there are generally three candidate causes: accidental damage (anchors, trawling, seabed landslides), environmental causes (earthquakes), or deliberate interference (sabotage or state/non‑state action).

• Historically, accidental anchor drag and fishing gear are the most frequent causes of cable faults worldwide.
• The Red Sea, however, has been a theatre of maritime conflict and asymmetric attacks for more than a year, including strikes on commercial shipping and incidents that left disabled vessels drifting — a known hazard that has in the past dragged anchors across cables and caused secondary damage.
• Security analysts and regional observers note that deliberate attacks on undersea infrastructure have been threatened and, in some episodes, suspected — but attributing a cable cut conclusively is technically challenging until maritime forensics and surveillance data are made public.

For journalists, cloud customers and policy makers, the responsible approach is to treat attribution carefully: explain the plausible causes, cite the behaviour and context that raise concern, and clearly label any attribution that remains unverified.

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The wider context: a year‑plus of regional incidents​

This September 2025 event did not occur in isolation. The Red Sea and adjacent waters saw multiple cable incidents in 2024 and into 2025:

• Previous damage tied to maritime attacks and to drifting, disabled vessels created months‑long outages and long repair timelines in prior incidents.
• Those earlier events revealed how insurance premiums, repair‑ship availability and security concerns constrain subsea maintenance and new installations.
• Policy debates about hardening undersea infrastructure and diversifying routes intensified after those earlier interruptions.

The repeated pattern magnifies two risks: first, that a series of cuts can create cumulative stress on global routing; second, that prolonged insecurity discourages new route investments and complicates repair logistics.

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Risk analysis: strengths, gaps and cascading consequences​

Strengths demonstrated​

• Network resilience: Cloud providers, including Microsoft, rapidly invoked alternate routing and peering strategies to keep services online for the vast majority of customers.
• Observability: Enhanced telemetry and third‑party monitoring groups detected and publicised the fault quickly, giving operators the situational awareness needed to act.
• Redundancy in practice: Where enterprises had multi‑region architectures or used local caching/CDN solutions, user impact was reduced.

Notable weaknesses and risks​

• Geographic concentration: A non‑trivial fraction of global intercontinental capacity funnels through a handful of chokepoints; this concentration creates systemic fragility.
• Repair bottlenecks: Security conditions and the scarcity of cable repair vessels make physical fixes slow and expensive.
• Economic and operational exposure: Financial markets, real‑time industrial systems, airline and logistics services, and latency‑sensitive cloud workloads are vulnerable to sudden path lengthening.
• Single‑provider assumptions: Customers who rely on single‑provider regional topologies or single undersea transit paths can see disproportionate effects.
• Geopolitical escalation risk: Repeated incidents raise the prospect that undersea infrastructure could be intentionally targeted in future conflicts, an escalation that would have broad economic consequences.

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Practical guidance for enterprise IT and cloud architects​

Enterprises should treat undersea cable disruptions as a tangible element of risk planning. Key mitigations include:

• Architect for multi‑region and multi‑provider redundancy
• Deploy critical workloads across at least two geographic regions and, where possible, across multiple cloud providers. This reduces the chance that a single corridor failure creates a total outage.
• Use CDNs, edge caching and read replicas
• Place static assets and read‑heavy services in edge caches and CDNs to reduce dependency on transcontinental round trips.
• Separate control and data planes
• Where low latency is required (financial feeds, real‑time control), minimise cross‑region control plane chatter and favour local processing.
• Implement BGP and routing resilience best practices
• Understand your transit providers, set realistic BGP policies, and test failover between alternative paths and peerings.
• Review SLAs and runbooks
• Ensure disaster‑recovery runbooks include undersea cut scenarios that account for prolonged physical repairs; test communications and failover procedures.
• Monitor experience (not just uptime)
• Track latency and transaction success rates — not only availability — since rerouting preserves connectivity but can degrade performance.

These steps are practical, cost‑effective and often complementary to general resilience principles already recommended for cloud‑native systems.

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What governments, navies and industry can and should do​

The vulnerability of subsea cables requires a blend of private‑sector engineering and public‑sector security and diplomacy:

• Protect repair operations: Establish clear international protocols and safe corridors for cable repair vessels in conflict zones, with military escorts where necessary to reduce repair delays.
• Encourage route diversity: Governments can incentivise investment in alternative routing — for example, northern or southern paths that bypass high‑risk corridors — through public funding, permitting support and tax incentives.
• Improve surveillance and forensics: Better maritime domain awareness (satellite, AIS, underwater monitoring) helps investigators determine cause and supports rapid attribution where intentional acts are suspected.
• Strengthen legal frameworks: International agreements to criminalise intentional damage to telecommunications infrastructure and to accelerate cross‑border cooperation for investigations will raise the cost of attacks.
• Public‑private drills and tabletop exercises: Regular joint exercises between operators, navies and policy agencies will speed coordination during real incidents.

Implementation of these steps requires political will and cross‑border cooperation; the technical community can provide the playbook, but governments must enable the security framework.

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The strategic picture: implications for cloud, AI and digital commerce​

Subsea cable fragility has strategic implications that go beyond transient slowdowns.

• Cloud economics and SLAs: Repeated regional disruptions increase the operational cost of delivering consistently low latency worldwide. Cloud providers will need to weigh the economics of further network investment versus relying on customer‑side mitigations.
• AI and large model workloads: AI training and inference often rely on massive, geographically distributed storage and compute. Increased transit latency or constrained bandwidth can raise costs and slow distributed training jobs.
• Financial markets and latency arbitrage: Markets that depend on microsecond timing can be particularly affected when long‑path detours shift latencies unpredictably.
• Regional digital sovereignty: Countries with limited route diversity are likely to accelerate investments in local caching, sovereign cloud infrastructure, and regional exchange points to reduce exposure to single chokepoints.

In short, repeated undersea cable incidents reshape both technical choices and commercial strategy for networks, cloud customers and sovereign actors.

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What is uncertain and what to watch next​

Several essential questions remain open or will require follow‑up:

• Attribution: Until maritime forensics and firm operator statements are released, whether the cuts were accidental or deliberate remains uncertain. Attribution affects the political and military response.
• Repair timeline: Physical repair schedules depend on ship availability, coastal permissions and security. Expect public updates as operators coordinate repair windows.
• Cumulative impact: If multiple cables are found to be impaired, the aggregated congestion could exceed what rerouting can absorb without noticeable service degradation in additional regions.
• Policy response: Watch for rapid shifts in policy discussions — at national parliaments and international forums — around undersea cable protection, insurance mechanisms and strategic network investments.

These open items will determine the practical and political consequences over the coming weeks and months.

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Bottom line​

The September 6, 2025 Red Sea cuts and the resulting Azure latency warnings are a stark reminder: the global internet depends on a small number of high‑value, physically exposed cables. Cloud providers can and did use routing, peering and redundancy to avoid catastrophic outages, but the event exposes systemic fragility that will not be fixed by software alone.
Enterprises must treat submarine cable risk as a real, enduring operational threat and adopt resilient architectures, while governments and industry should accelerate measures to protect, diversify and provide safe conditions for subsea maintenance. Without coordinated technical, commercial and security responses, similar incidents will continue to produce outsized effects on cloud performance, commerce and national resilience.
Enduring resilience requires three concurrent actions: practical engineering by operators and customers, sustained investment in alternative routes and repair capacity, and international cooperation to keep the arteries of the global internet open and secure.

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Source: webdo.tn Microsoft alerts on an underwater cable cut in the Red Sea