A U.S. judge on Thursday blocked the Pentagon’s blacklisting of Anthropic, the latest turn in the Claude maker’s high-stakes fight with the military over AI safety on the battlefield.Anthropic’s lawsuit in California federal court alleges that Defence Secretary Pete Hegseth overstepped his authority when he designated Anthropic a national security supply-chain risk, a label the government can apply to companies that expose military systems to potential infiltration or sabotage by adversaries.Hegseth’s unprecedented move, which blocked Anthropic from certain military contracts, followed Anthropic’s refusal to allow the military to use its Claude AI models for U.S. surveillance or autonomous weapons. Anthropic executives have said it could cost the company billions of dollars in lost business and reputational harm.U.S. District Judge Rita Lin, an appointee of former Democratic President Joe Biden, issued a 59-page order ruling that the Pentagon’s decision was “illegal and baseless.”“The empty invocation of national security is not a blank check to punish and retaliate against government critics,” she wrote.Anthropic welcomed the ruling and said in a statement that it remained “focused on working productively with the government to harness AI for our national security so all Americans benefit from this technology.”The Pentagon did not immediately respond to a request for comment.Anthropic argues that AI models are not reliable enough to be safely used in autonomous weapons and that it opposes domestic surveillance as a violation of rights, but the Pentagon says private companies should not be able to constrain military action.The designation made by the Pentagon was the first time a U.S. company has been publicly designated a supply-chain risk under an obscure government-procurement statute aimed at protecting military systems from foreign sabotage.In its March 9 lawsuit, Anthropic alleged the government violated its right to free speech under the First Amendment of the Constitution by retaliating against its views on AI safety. The company said it was not given a chance to dispute the designation, in violation of its Fifth Amendment right to due process.The lawsuit says the decision was unlawful, unsupported by facts and inconsistent with the military’s past praise of Claude.The Justice Department countered that Anthropic’s refusal to lift the restrictions could cause uncertainty in the Pentagon over how it could use Claude and risk disabling military systems during operations, according to a court filing.The government said the designation stemmed from Anthropic’s refusal to accept contractual terms, not its views on AI safety.Anthropic has a second lawsuit pending in Washington, D.C., over a separate Pentagon supply-chain risk designation that could lead to its exclusion from civilian government contracts.