BT joins Anthropic’s Project Glasswing for AI cyber defence

TL;DR:

  • BT is the first UK company to confirm membership of Anthropic’s Project Glasswing, a programme securing critical infrastructure with frontier AI.
  • Membership grants access to Claude Mythos Preview to rapidly identify and fix vulnerabilities before attackers exploit them.
  • BT says it already blocks four million cyber-attacks across its networks every day.

BT has become the first UK company to confirm it has joined Anthropic’s Project Glasswing, the programme that gives critical infrastructure providers access to frontier AI to harden their systems. Through it, BT gains access to Claude Mythos Preview — Anthropic’s frontier model — to find vulnerabilities across the networks millions of people and businesses depend on, and patch them before criminals strike.

Frontier AI moves to the defenders’ side

The announcement came as chief executive Allison Kirkby opened the government’s AI Adoption Summit, attended by Chancellor Rachel Reeves and Technology Secretary Liz Kendall. Kirkby argued “AI only works at scale when it is underpinned by future-ready networks that are secure, resilient, safe”, and pledged BT’s support for “sovereign British AI capability” so the UK can be “an AI maker and not just a taker”. BT, which says it now prevents four million attacks a day, also recently partnered with Accenture on AI-powered cyber operations that respond “at machine speed”.

The move is notable because Anthropic’s Mythos model has featured on both sides of the security ledger. Recent reporting documented the same family being used to help low-skill hackers adopt expert tactics and being deployed by the NSA for offensive cyber work. Glasswing represents the defensive counterweight — putting the same capability in the hands of infrastructure operators.

Looking forward

For UK businesses, BT’s move is a concrete adoption case rather than a vendor pitch: a major operator of critical national infrastructure betting that frontier AI is now necessary to keep pace with AI-armed attackers. It also strengthens the UK’s “AI maker” positioning at a moment when financial regulators are warning banks about exactly this threat. The harder question for smaller firms — without BT’s scale or a seat in Glasswing — is how they access comparable protection.

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