On May 30, 2026, on the sidelines of the 23rd Shangri-La Dialogue in Singapore, seventeen countries launched GUIDE — the Guiding Principles for Underwater Infrastructure Defence Exchanges. Initiated by Singapore, the signatories include eight EU member states (France, Italy, the Netherlands, Sweden, Finland, Estonia, Latvia and Lithuania) alongside the UK, Australia, New Zealand, Qatar, and four ASEAN neighbours. According to Singapore's Ministry of Defence, GUIDE is "an agreement of shared principles" for collaboration on critical underwater infrastructure (CUI) security — not a treaty, not a funding vehicle, and explicitly not a source of new legal obligations.
That last point is the most important, and the most misunderstood.
The threat is real, and so is the case for hard rules
The damage record is not hypothetical. Defense News reported that at least 11 cables in the Baltic Sea were damaged in the fifteen months after October 2023, prompting NATO to launch its Baltic Sentry surveillance mission on January 14, 2025. In the Taiwan Strait, a Togo-flagged, Chinese-crewed vessel severed the TP3 cable in February 2025; its captain was later convicted and sentenced to three years — the first criminal conviction of its kind. A 2023 incident left the 14,000 residents of Taiwan's Matsu islands without reliable internet for two months.
So the steelman for binding regulation is strong. More than 95% of the world's data traffic travels under the ocean. When a fishing trawler or a "shadow fleet" tanker can drag an anchor across a transcontinental artery and disappear into the legal gray zone beyond territorial waters, the case for enforceable rules — mandatory vessel tracking, compulsory reporting, agreed rights of interdiction — is intuitive. A voluntary memo can feel like a press release dressed as a policy.
Why the soft-law design is a feature, not a bug
But the binding-treaty instinct collides with the actual geography of the problem. Subsea cables cross the high seas, where the 1982 UN Convention on the Law of the Sea (UNCLOS) sharply limits what any state may do to a foreign-flagged ship. GUIDE is carefully drafted so that it "does not create new legal obligations nor prejudice existing rights and obligations under international law, including UNCLOS," as the framework's text — summarized by subsea-industry specialist Submarine Networks — makes explicit.
This is the right call. A binding instrument that tried to expand interdiction rights on the high seas would have either died in negotiation or invited reciprocal claims from the very states most suspected of sabotage. By staying inside UNCLOS rather than trying to rewrite it, GUIDE sidesteps a decade of treaty-drafting and delivers the one thing operators actually need now: faster information flow. The framework commits signatories to "enhancing inter-regional information-sharing to support maritime awareness and early warning" and to exchanging permanent points-of-contact for crisis response. For an incident measured in hours — a cut cable rerouting petabytes and triggering repair-ship dispatch — a shared early-warning channel is worth more than a paper right to board a ship you cannot find.
Crucially, the soft-law design is what made the coalition possible. As the framework's own logic notes, defence establishments "play a supporting role rather than a lead one," so a voluntary structure "lowers the political barriers to entry while still enabling meaningful information sharing." Seventeen countries across three regions signed in one sitting precisely because nobody had to ratify anything or surrender sovereignty. A binding pact would likely have produced three signatures and a multi-year impasse.
Complement, not competitor, to the EU's harder track
For the EU members at the table, GUIDE layers neatly on top of Brussels' more muscular domestic effort. The EU Action Plan on Cable Security, adopted on February 21, 2025, organizes work around four pillars — prevention, detection, response and recovery, and deterrence — and is backed by real money: the Commission has channelled hundreds of millions through the Connecting Europe Facility, with a further €347 million flagged for 2026–2027, an EU Cable Vessels Reserve to speed repairs, and a Hybrid Toolbox to sanction hostile actors.
That division of labour is sensible. The EU spends and regulates inside its own jurisdiction, where it has authority; GUIDE handles the cross-regional intelligence-sharing that no single bloc can mandate. Hard law where you have jurisdiction, soft coordination where you do not — that is proportionate regulation, not a cop-out.
The real test is whether the absent powers ever join
The framework's obvious weakness is its guest list. The United States, China, Russia, Japan, India and South Korea all stayed out — the very states that operate the largest cable networks and the most capable maritime surveillance fleets. A cable-defence club without Washington or Tokyo has real blind spots, and a club whose chief suspects are not members cannot deter them directly.
But this is an argument for GUIDE's flexibility, not against it. A voluntary framework can add members without re-ratification; a treaty cannot. The smart move is to treat GUIDE as a nucleus — prove the information-sharing works among willing partners, then expand. Regulators worldwide reaching for the cable-security file should take the lesson: when the asset is global and jurisdiction is fractured, a fast, voluntary, UNCLOS-respecting network beats a slow, comprehensive treaty that never enters force. GUIDE is the kind of light-touch coordination that actually ships.