Microsoft has made its most comprehensive public case yet that responsible AI development and effective national defense must coexist, filing a court brief in a San Francisco federal court in support of Anthropic’s lawsuit against the Pentagon’s supply-chain risk designation. The brief called for a temporary restraining order and argued that the designation undermines both commercial AI and national defense by disrupting critical technology supply chains. Amazon, Google, Apple, and OpenAI have also backed Anthropic through a joint filing.
Anthropic’s lawsuit was triggered by the Pentagon’s decision to label it a supply-chain risk after the company refused to allow its Claude AI to be used for mass surveillance of US citizens or to control autonomous lethal weapons during a $200 million contract negotiation. Defense Secretary Pete Hegseth formalized the designation following the breakdown of talks, and Anthropic’s government contracts began to be cancelled. The company filed two simultaneous lawsuits in California and Washington DC.
Microsoft’s comprehensive case for the coexistence of responsible AI and defense is grounded in its direct integration of Anthropic’s technology into military systems and its participation in the Pentagon’s $9 billion cloud computing contract. The company also holds additional federal agreements with government agencies. Microsoft publicly called for a collaborative framework in which government and industry jointly define responsible standards for AI use in national security.
Anthropic’s court filings argued that the supply-chain risk designation was an unconstitutional act of retaliation for the company’s publicly stated AI safety positions. The company disclosed that it does not currently believe Claude is safe or reliable enough for lethal autonomous operations, which it said was the genuine basis for its contract demands. The Pentagon’s technology chief publicly ruled out any possibility of renewed negotiations.
Congressional Democrats have separately asked the Pentagon whether AI was involved in a strike in Iran that reportedly killed over 175 civilians at a school, demanding information about AI targeting systems and human oversight. Their inquiries are adding legislative urgency to a legal battle that is forcing a national conversation about how to make responsible AI and effective national defense coexist. Microsoft’s comprehensive case for coexistence may ultimately become the framework around which that conversation is organized.