Microsoft has committed to Anthropic’s legal defense as the AI company’s case against the Pentagon’s unprecedented supply-chain risk designation prepares for a critical court hearing, filing an amicus brief in a San Francisco federal court calling for a temporary restraining order. The brief argued that the designation threatens critical technology supply chains relied upon by national defense. Amazon, Google, Apple, and OpenAI have similarly committed to Anthropic’s defense through a joint supporting filing.
The case heading to court arose from a $200 million contract negotiation in which Anthropic refused to allow its Claude AI to be used for mass surveillance of US citizens or autonomous lethal weapons. Defense Secretary Pete Hegseth labeled the company a supply-chain risk, triggering the cancellation of Anthropic’s government contracts. Anthropic filed two simultaneous lawsuits in California and Washington DC challenging the designation.
Microsoft’s commitment to Anthropic’s 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. Additional federal agreements spanning defense, intelligence, and civilian agencies further deepen Microsoft’s stake. Microsoft publicly called for a collaborative approach between government and industry to ensure advanced AI served national security responsibly.
Anthropic’s court filings argued that the supply-chain risk designation was an unconstitutional act of retaliation for its publicly stated AI safety positions. The company disclosed that it does not currently believe Claude is safe or reliable enough for lethal autonomous operations. The Pentagon’s technology chief publicly ruled out any renegotiation.
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 answers about AI targeting and human oversight. As the court hearing approaches, Microsoft’s commitment, the industry coalition, and congressional pressure are creating an extraordinary level of support for Anthropic that may prove decisive in determining the outcome of this landmark case.