Microsoft has broken what many in the industry viewed as a collective silence on AI ethics in military contexts, filing a landmark court brief in a San Francisco federal court in support of Anthropic’s battle against the Pentagon’s supply-chain risk designation. The brief called for a temporary restraining order and argued that the designation poses a severe threat to the technology networks that support national defense. Amazon, Google, Apple, and OpenAI have also filed in support of Anthropic, creating an unprecedented coalition of corporate voices on AI ethics in national security.
Anthropic’s legal challenge was triggered by the Pentagon’s decision to label it a supply-chain risk after it refused to allow its Claude AI to be used for mass surveillance of US citizens or to power autonomous lethal weapons as part of a $200 million contract. Defense Secretary Pete Hegseth formalized the designation, leading to the cancellation of Anthropic’s government contracts. The company filed two simultaneous lawsuits in California and Washington DC arguing the designation was unconstitutional.
Microsoft’s landmark filing is grounded in its own direct use of Anthropic’s AI in federal military systems and its participation in the Pentagon’s $9 billion cloud computing contract. The company also holds additional agreements with defense, intelligence, and civilian agencies. Microsoft publicly called for a collaborative approach between government and the technology sector to ensure AI serves national security responsibly.
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 decision-making, which it said was the genuine basis for its contract demands. The Pentagon’s technology chief publicly ruled out any possibility of renegotiation.
Congressional Democrats have separately pressed the Pentagon for answers about whether AI was involved in a strike in Iran that reportedly killed more than 175 civilians at a school. Their formal inquiries ask about AI targeting tools and human oversight. The combination of Microsoft’s landmark filing, the industry coalition, and congressional pressure is breaking the silence on AI ethics in military contexts and forcing a long-overdue public debate.