Japan will quickly implement a response package to address cyber-attack risks posed by the new AI model Claude Mythos [1].

This move comes as the government recognizes the potential for advanced artificial intelligence to be exploited for sophisticated attacks against critical infrastructure. By developing specific countermeasures, Japan aims to secure its digital systems while simultaneously pursuing a strategy to make the technology accessible to the public.

Digital Minister Naoto Matsumoto announced the initiative on May 12, 2026 [1], following a cabinet meeting in Tokyo. Matsumoto said there were instructions to quickly materialize and implement the response [1]. The minister said he wants to make the AI openly available in the near future, suggesting a balance between national security and technological openness [1].

The urgency of the situation is underscored by warnings from other officials. Hira Masaharu, a former Digital Minister, said the government should strengthen its measures against the increasing sophistication of cyber attacks [1].

The government's approach involves a two-pronged strategy: mitigating the immediate risk of exploitation and fostering an environment where AI can be used for innovation. The response package is intended to bridge the gap between the rapid release of high-capability models and the slower pace of traditional security updates.

While the cabinet meeting on May 12 [1] set the immediate directive, political pressure for these defenses has been building. The Liberal Democratic Party submitted a request to the government regarding these measures on May 20, 2026 [2].

“Japan will quickly implement a response package to address cyber-attack risks posed by the new AI model Claude Mythos.”

Japan's decision to create a dedicated response package for Claude Mythos reflects a shift toward 'model-specific' national security policies. Rather than general AI regulation, the government is treating high-capability models as specific vectors for cyber threats. The tension between the desire to make the AI 'open' and the need to defend against its misuse highlights the global struggle to balance open-source innovation with the prevention of automated, large-scale cyber warfare.