Microsoft has filed an amicus brief in support of Anthropic, the AI company challenging a Pentagon designation that effectively bars it from government work. The brief, submitted to a federal court in San Francisco, argues that a temporary restraining order is necessary to prevent disruption to suppliers relying on Anthropic's technology. Google, Amazon, Apple and OpenAI have also signed on to a similar brief.
The dispute stems from collapsed contract negotiations over a $200m deal to deploy Anthropic's AI on classified military systems. Talks fell apart after Anthropic insisted its technology should not be used for mass surveillance of US citizens or to power autonomous lethal weapons, leading Defense Secretary Pete Hegseth to label the company a supply-chain risk. The Pentagon has since begun cancelling government contracts with Anthropic.
In its complaint, Anthropic stated it does not have confidence that its AI system, Claude, would function reliably in lethal autonomous warfare. The company argues the Pentagon's designation violates its First Amendment rights, claiming it is ideological punishment for its public stance on AI safety. The designation has never before been applied to a US company.
Microsoft, a key Pentagon tech partner holding a share of the $9bn Joint Warfighting Cloud Capability contract, said in a statement: “The Department of War needs reliable access to the country’s best technology. And everyone wants to ensure AI is not used for mass domestic surveillance or to start a war without human control.”
Separately, a Pentagon investigation into a Tomahawk strike on a school in Iran that killed at least 175 people has reportedly found Washington responsible, likely due to a targeting mistake based on outdated data. House Democrats have pressed the Pentagon on the role of AI in target selection, asking whether systems like Maven Smart System were used.
