Professor Maximiano, when we talk about submarine cable resilience, what do we mean and what exactly are the threats we’re concerned about?
Resilience means the capacity of submarine cable infrastructure to withstand, adapt and, most importantly, quickly recover from incidents.
These include accidental damage, such as fishing or anchoring, and natural causes such as earthquakes or landslides. There are also geopolitical threats from intentional sabotage and cyber intrusions. However, these are less common than the general perception. For example, in the Baltic Sea in late 2024 and early 2025, an incident first attributed to sabotage turned out, after investigation, to be accidental. So this idea that most damage is caused by sabotage is wrong – it’s usually accidental. Nonetheless, cables can never be 100 per cent protected. It’s why resilience and rapid repair capacity are critical, regardless of the cause.
Why is Portugal so prominent in this debate?
Portugal has a privileged geographical position. It sits on the western edge of Europe, facing the Atlantic. We are literally a crossroads between Europe, Africa and the Americas. Our islands – the Azores and Madeira – are in different continents and span tectonic plates.
This gives Portugal a strategic role as a digital gateway. We’ve embraced that role by pushing submarine cable resilience onto both the European and global agenda.
Our flagship initiative is the Atlantic CAM (Continente, Açores, Madeira) project. It’s a new cable system connecting mainland Portugal with our islands. It uses a resilient ring topology and, crucially, it will be the world’s first fully operational ‘smart cable’ (science monitoring and reliable telecommunication).1 The cable integrates sensors that collect oceanographic and seismic data alongside carrying telecommunications traffic.
That data has multiple uses, including tsunami detection, support for scientific research and, more controversially, underwater surveillance.
Because many incidents are accidental, these sensors help detect risks early and trigger preventive action. But there are sensitivities, particularly when data could also be used for defence purposes. Smart cables generate classified information. That means cooperation between ministries, regulators, defence bodies, private operators and academia – all groups that traditionally operate separately. Building that cooperation is difficult but essential.
It’s also a governance issue. Who handles the data? In Portugal, scientific data will go to the University of Madeira, but anything that touches on national security must go through defence channels.
Many new submarine cables are funded by big tech companies. The Atlantic CAM cable is publicly funded. Isn’t that unusual?
It is less common today, but not unprecedented. The Portuguese government, with EU support, is funding the CAM system because it is about territorial cohesion as well as connectivity. Remote regions cannot always rely on private investment alone.
The construction is being managed by Alcatel Submarine Networks Portugal, a public company. The cable replaces an older system that is reaching its end of life.
So while global tech giants build large transoceanic cables for data centre traffic, states still have a role in ensuring connectivity to less commercially attractive regions.
Some companies are experimenting with burying cables to reduce accidental damage. Is that practical?
Only in relatively shallow waters where most damage occurs. Near the coast, cables are often reinforced and sometimes buried. In the deep ocean, cables are thinner and more exposed.
Fully protecting a subsea cable isn’t realistic – it would be extremely expensive and make it even more expensive to repair. That’s why our focus is shifting to quick repair and maintenance capacity.
What does ‘quick repair’ mean in practice?
It comes down to three things: the availability of specialised repair vessels and spare components; the coordination of responsibilities (which are often fragmented between different national bodies); and legal clarity about who can act, and in which waters.
Resilience is not just about the cables themselves; it is about the entire ecosystem that keeps them working.
At present, Europe’s submarine cables are on average 17 years old. Repair times can be long and small countries or remote islands often wait far too long for restoration.
That’s why we argue cables must be formally recognised as critical infrastructure, with clear regulation to ensure a rapid response.
Governments do not own repair vessels. Operators hire companies that manage both landings and repairs. The problem is that demand often outstrips capacity. Repairs may be delayed because vessels are already contracted elsewhere. That’s why international coordination and prioritisation are so important.
How is the EU responding?
The European Commission is developing a cable security toolbox, modelled on the 5G security toolbox. It will provide recommendations on resilience, security standards and supply-chain issues.
In Portugal, we also run national stress tests under the Network and Information Systems Directive (NIS2) and the Critical Entities Resilience Directive (CER). These exercises bring together ministries, regulators, the navy, coastguards, private operators and academia.
By simulating incidents, we test roles, coordination and response times. Last year Portugal conducted its first national-level subsea cable security drill. We learned a great deal and no cables were harmed! The aim is to produce a toolkit to help guide other countries to develop effective responses.
Portugal also hosts several major international cables, doesn’t it?
Yes, beyond our national CAM system, we host landings for some of the world’s most important cables such as EllaLink, connecting Brazil to Europe via Portugal, Equiano (Google), linking Europe, Africa and the US, and SEA-ME-WE 6 (a cable connecting South East Asia, the Middle East and Western Europe currently under construction). Ensuring the security of these cables is an extra responsibility that we take very seriously.
Recently, two new systems were announced: Nuvem and Sol, which will enhance connectivity between North America and Portugal.
And at the global level, you’re involved in UN and ITU initiatives?
I co-chair the ITU Advisory Body on Submarine Cable Resilience, established within the International Cable Protection Committee (ICPC).2 It brings together 40 experts from governments, regulators, industry and academia. We focus on best practice, cooperation and support for regions without strong economic incentives for resilience, especially small islands and developing countries.
In February 2025, we adopted the Abuja Declaration, a milestone in promoting international cooperation. The advisory body has now established three thematic working groups tasked with delivering concrete outcomes: ‘Resilience by Design’ concentrates on ensuring redundancy and diverse routes; ‘Timely Deployment and Repair’ is addressing regulatory barriers to fast action; the ‘Security and Monitoring’ group focuses on identifying and mitigating risks, including through new technologies like smart cables. There will be reports published on each of these themes.
The UN has now established a joint task force aimed exclusively at developing a global smart subsea cable network.3
I am also happy to announce that next year’s International Submarine Cable Resilience Summit will take place in Portugal.
Do big tech companies, the likes of Google and Microsoft, participate in these discussions?
Yes. Private sector participation is crucial. The group includes regulators, governments, infrastructure operators and technology companies. The ITU has made an effort to ensure broad stakeholder representation.
Where do disagreements arise?
The most sensitive issue is sensor technology. Smart cables can detect earthquakes but they can also detect submarines. That inevitably raises defence questions. Standardisation discussions can also be delicate and have to take account of the competencies and regulatory structures of each country, as well as recognising that different countries do things in different ways.
Because our group is explicitly non-political, we try to keep the focus on scientific and resilience benefits. Still, it requires careful handling to avoid undermining trust.
You mentioned small countries suffering most when repairs are delayed. Could you expand?
For a big operator, the loss of one part of a cable may be commercially marginal. For a small island, it can mean total national disconnection.
We’ve seen countries go without connectivity for weeks.4 In today’s digital society, where education, healthcare and government services all depend on broadband, that is catastrophic.
That’s why resilience is also a development issue. We cannot allow economic logic alone to dictate repair priorities.
We’ve talked a lot about connectivity, but how does energy resilience intersect with cable resilience?
They are deeply linked. Last year, there was a total loss of power across Iberia for an entire day. Telecoms operators have battery back-up but they’re designed to last for a few hours. Batteries cannot cover a full day.
That showed the importance of energy prioritisation for telecoms. Resilience is not just about the cables themselves; it is about the entire ecosystem that keeps them working.
Looking ahead, are you optimistic about submarine cable resilience?
Yes, I am. Submarine cables are now firmly on the EU and UN agenda and there is growing international cooperation; new technologies like smart cables have the ability to create a step change in resilience.
Sandra Maximiano was speaking to Russell Seekins.
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