Spain accelerates digital defenses against Anthropic's Mythos AI vulnerability tool

Spain's defense establishment is moving fast. In recent weeks, officials across the government have begun accelerating the country's digital defenses in response to a single tool: Claude Mythos Preview, an artificial intelligence system built by the American company Anthropic. The tool can identify software vulnerabilities in seconds—flaws that human teams and automated security tests have missed for decades. In the wrong hands, cybersecurity experts warn, it could become the most powerful offensive weapon ever deployed against critical infrastructure.

The architecture of digital defense works like a medieval fortification. Security specialists search constantly for weaknesses in the walls—gaps in code, overlooked pathways, unpatched systems—and rush to seal them before attackers find them. It is exhausting, endless work. But imagine if a single machine could do that work at machine speed, scanning vast codebases and identifying every crack in the wall in moments, without human involvement. That machine now exists. Anthropic created it in near-total secrecy until word leaked that the company had given access to a small group of American technology firms: Apple, Microsoft, Amazon. These companies are using Mythos to harden their own defenses before the tool becomes widely available.

The problem, from Madrid's perspective, is that Mythos has not yet reached Europe. None of the 27 EU member states has access to it. Neither do the continent's major banks or financial institutions, at a moment when the European Central Bank has explicitly asked governments to strengthen their cybersecurity plans in anticipation of the tool's arrival. David Pérez Cid, the director of Financial Stability, Regulation and Resolution at Spain's central bank, put it plainly: in a world as interconnected as ours, it would be reasonable to expect that everyone could prepare their defenses together. Instead, Europe is watching from the outside while American companies get a head start.

The Spanish government believes the response must be coordinated at the European Commission level, though Brussels has so far been unable to secure access to Mythos. Internally, though, Spain is moving. Esperanza Casteleiro, the director of Spain's National Intelligence Center, announced this week that the Defense Ministry has accelerated the reinforcement of the country's digital shield, redesigning its architecture in response to the emergence of this new artificial intelligence. She did not say the word Mythos aloud, but people close to her made clear that every eye in the intelligence community focused on cybersecurity is now fixed on Anthropic's tool.

The stakes are not abstract. If Mythos fell into hostile hands, the consequences would extend far beyond the theft of personal data—though that alone would be catastrophic. The tool could be weaponized against critical infrastructure: the electrical grids and nuclear plants that power the country, the ports and airports and rail networks that move people and goods, the hospitals and health data systems that sustain public health, the crisis management centers and government ministries that hold the keys to national security. An attacker who used Mythos to find multiple vulnerabilities in a single system could chain those exploits together, gaining complete control.

Police sources describe the challenge as nearly insurmountable. They compare it to Spain's long struggle against ETA, the Basque separatist organization, where technological superiority—wiretaps, surveillance, intelligence gathering—ultimately tipped the balance. Now, without access to Mythos, cybersecurity officials find themselves at a clear disadvantage. The tool represents an asymmetry that cannot easily be closed.

But the crisis has also surfaced a deeper problem that Spanish officials believe has been dormant too long: Europe's technological dependence on the United States. Anthropic's Mythos is a case study in that vulnerability. A single American company has built a tool so powerful that it reshapes the security landscape, and Europe has no seat at the table. The Spanish government has begun to echo the words of Teresa Ribera, the European Commission's executive vice president, who has insisted that Europe must develop its own capabilities. The fear of Mythos, paradoxically, may be the catalyst that finally forces the continent to act on that imperative.