The Japanese government convened an inter-ministerial meeting on Monday to coordinate counter-measures against the new AI model Claude Mythos [1].

This move signals an urgent shift in national security strategy as governments grapple with AI's ability to automate the discovery of system vulnerabilities. Because the model can rapidly identify security gaps, officials fear it could be weaponized to launch sophisticated cyber-attacks against the nation's most essential services.

Digital Minister Matsumoto said the government would shift gears multiple times to build resilience at the world's highest level [1]. As part of this coordinated response, the government issued cautions to 15 critical-infrastructure operators [1]. These operators are being urged to engage in rapid information exchange, and adopt defensive AI tools to protect their systems.

Claude Mythos was developed by the U.S.-based company Anthropic [3]. The Japanese government's strategy focuses on utilizing high-performance AI to find and fix vulnerabilities before they can be exploited by malicious actors [2].

Chief Cabinet Secretary Minoru Kihara said the government is rushing its response based on concerns that the latest AI models could be abused for cyber-attacks [2]. The meeting on May 18, 2026, marks the first formal inter-ministerial effort to specifically target the threats posed by this particular model [2].

Government officials said they have compiled a set of response measures to ensure that critical infrastructure remains secure against AI-driven threats [2]. The strategy emphasizes a proactive defense, moving away from reactive patching toward a model of continuous, AI-assisted vulnerability management.

“The government issued cautions to 15 critical-infrastructure operators.”

This development highlights a growing 'AI arms race' in cybersecurity. By urging infrastructure operators to use AI defensively to counter an AI-driven threat, Japan is acknowledging that human-led security audits are no longer sufficient to keep pace with the speed of automated vulnerability discovery. The focus on Claude Mythos suggests that the capabilities of the latest large language models have reached a threshold where they are viewed as systemic risks to national security.