US ambassador to Lisbon pressures Portugal over undersea cables security guarantees

The US ambassador to Portugal, John Arrigo, has suggested that Portugal step up its security of undersea transatlantic cables linking the two countries.

According to news source Expresso, the ambassador issued a clear warning during a recent conference organised with the Luso-American Foundation for Development (FLAD):

“This (transatlantic relationship) only works with a secure infrastructure and broader economic security. While Portugal invests in security research, it cannot compromise its communications infrastructure.”

The diplomat stressed that investments from technology giants such as Microsoft, Google, Meta, and Amazon are at stake, and their reliability depends on the robustness of security guarantees.

The warning comes amid security concerns also stated in the Annual Report of Internal Security about Russian ships mapping the submarine cables on the sea bed and stressing that despite these threats Portugal’s government has not yet defined a strategy to protect them from sabotage.

The annual report (RASI) 2025, which was released earlier this month, identified “concerns” from the Portuguese authorities during 2025 “about the “possible preparation of acts of sabotage, particularly on critical infrastructures such as submarine cables.”

However, Portugal has yet to approve its National Strategy for Critical Infrastructures which should have been approved in January and which is drawn up by the General Secretary for the Internal Security System (SSI).

Portugal is a strategic hub for submarine cables, connecting more than 20 international cables that underpin the global internet, with main stations in Carcavelos, Sesimbra, and Sines. Its Atlantic location links Europe to America and Africa, with new projects like EllaLink and 2Africa reinforcing digital sovereignty.

Submarine cables carry 95% of internet data between the two countries and 75% of all other data, and the US ambassador said that “Portugal could not put communication infrastructures at risk because it could put huge investments in technology (such as data centres) at risk.

If these cables were to be cut or damaged, it would put modern society at risk affecting internet, data communication, bank transfers, disruptions to the financial markets and even hospitals.

Since the War in Ukraine started in February 2022, there has been an uptick in the location and mapping of submarine cables by Russian surveillance vessels in the Atlantic and North Sea.

The Portuguese Navy (Marinha Portuguesa) currently operates a fleet centered on two Trident-class (U 209PN) submarines, five frigates (three Vasco da Gama and two Bartolomeu Dias classes), and several patrol vessels. They are upgrading with new assets, including the NRP D. João II multi-purpose vessel slated for 2026.

Portugal currently has two submarines: NRP Trident (S160) and NRP Arpão (S161) and several frigates: the NRP Vasco da Gama (F330), NRP Álvares Cabral (F331), NRP Corte-Real (F332), NRP Bartolomeu Dias (F333), NRP D. Francisco de Almeida (F334).

It also has the patrol vessels including Viana do Castelo-class oceangoing patrol ships and Tejo-class coastal patrol vessels.

Among new acquisitions are the NRP D. João II (Multi-Purpose Vessel/Drone Carrier) set for 2026.

The navy also maintains auxiliary ships, including logistical support ships, specialised research vessels, and training ships.

Sources: Expresso/Portuguese Navy; Credits: US Embassy, Lisbon