Anthropic’s Pentagon blacklist struck down: How the conflict unfolded

| Date | Event | | --- | --- | | January 29 | The Pentagon and Anthropic clash over eliminating safeguards that could allow the government to use its technology to target weapons autonomously and conduct U.S. domestic surveillance | | February 23 | U.S. Defense Secretary Pete Hegseth summons Anthropic CEO Dario Amodei to the Pentagon for talks on the military use of Claude | | February 24 | The Pentagon asks Anthropic to get on board, or risk consequences, including being labeled a supply-chain risk | | February 25 | The Pentagon asks defense contractors, including Boeing BA.N and Lockheed Martin LMT.N, to assess their reliance on Anthropic | | February 26 | Pentagon spokesperson Sean Parnell gives Anthropic a deadline to allow unrestricted military use of its technology until 5:01 p.m. ET on February 27 | | February 26 | Anthropic refuses to eliminate safeguards from its AI systems | | February 27 | U.S. President Donald Trump directs every federal agency to immediately cease all use of Anthropic's technology | | February 27 | Hegseth directs the U.S. DoD to designate Anthropic a "supply-chain risk to national security" | | February 27 | Anthropic says it will challenge in court the Pentagon's decision | | February 27 | OpenAI announces deal to deploy technology in the DoD's classified network, which includes three conditions | | March 2 | The U.S. Departments of State, Treasury and Health and Human Services move to cease using Anthropic's Claude | | March 3 | Lockheed Martin pledges to follow the DoD's direction, signaling a wider contractor exodus, legal experts say | | March 4 | Big tech industry group pushes to de-escalate the clash, saying a supply-chain risk designation creates uncertainty for companies and could threaten the military's access to the best products and services | | March 5 | The U.S. DoD formally designates Anthropic as a supply-chain risk | | March 6 | The U.S. General Services Administration terminates Anthropic's OneGov deal, which made Claude available to the federal government | | March 9 | Anthropic sues to block the Pentagon from placing it on a national security blacklist, calling it unlawful and a violation of its free speech and due process rights | | March 9 | Anthropic executives say the U.S. government's blacklisting of the AI firm could cut its 2026 revenue by multiple billions of dollars and cause reputational harm | | March 10 | Microsoft MSFT.O backs Anthropic's lawsuit, warning the designation risks costly supplier disruptions and rushed rebuilding of products that depend on Anthropic | | March 11 | Pentagon tells senior leaders that Anthropic's tools may continue beyond the phase-out if deemed critical to national security, internal memo shows | | March 12 | Anthropic sought a stay from the U.S. Court of Appeals for the District of Columbia Circuit of the Pentagon's supply-chain risk designation | | March 12 | Pentagon Chief Technology Officer Emil Michael rules out negotiations with Anthropic | | March 17 | U.S. President Donald Trump's administration says Anthropic is unlikely to prevail on its First Amendment claims | | March 24 | During a court hearing, U.S. Judge Rita Lin of the District Court for the Northern District of California says the Pentagon's blacklisting of Anthropic "looks like an attempt to cripple Anthropic" for raising AI safety concerns | | March 26 | Lin temporarily blocks the Pentagon's blacklisting, giving the administration seven days to appeal | | April 8 | A panel of the U.S. Court of Appeals for the District of Columbia Circuit declines to pause the supply-chain risk designation, allowing the blacklisting to remain during the legal challenge | | April 13 | Anthropic co-founder Jack Clark says the company is discussing the capabilities of its advanced AI model, Mythos, with the Trump administration | | April 16 | The White House prepares to give major federal agencies access to a version of Mythos, Bloomberg News reports | | April 19 | The U.S. National Security Agency is using the Mythos Preview model, with the tool reportedly being used more broadly within the Defense Department, Axios reports | | April 21 | Trump says Anthropic is "shaping up" and signals a potential deal with the Pentagon after recent White House talks | | April 28 | The White House drafts guidance that could let federal agencies bypass the designation and use new models such as Mythos, Axios reports | | May 1 | Pentagon strikes classified-network deals with seven AI firms, including OpenAI, Google and Microsoft, while Anthropic remains excluded | | May 12 | Pentagon technology chief says the Defense Department is using Mythos to identify and patch cybersecurity vulnerabilities | | June 5 | Anthropic and the White House are easing tensions ahead of the company's planned IPO, sources tell Reuters | | June 8 | The Trump administration denies unlawfully retaliating against Anthropic over its military AI guardrails | | June 12 | Anthropic disables Fable 5 and Mythos 5 after a U.S. government order restricting foreign access | | June 23 | U.S. Senator Mark Warner says Mythos identified vulnerabilities in classified U.S. government systems within hours, the Associated Press reports | | June 30 | The U.S. Commerce Department lifts export controls on Fable 5 and Mythos 5 after Anthropic implements new safeguards | | July 6 | The U.S. Cybersecurity and Infrastructure Security Agency is using Mythos to scan government software, with the audits reportedly uncovering numerous bugs, Reuters reports | | August 27 | Lin permanently blocks the Pentagon's blacklisting of Anthropic, ruling the designation was "illegal and baseless" | Aug. 28 (Reuters) - A U.S. judge on Thursday permanently blocked the Pentagon's "supply-chain risk" designation against Anthropic, ending a months-long standoff over military access to the company's frontier AI models. The dispute began early this year when the Pentagon pressed Anthropic to remove safety guardrails from Claude, a demand that escalated into a blacklisting and triggered lawsuits and federal agency bans. Despite the ban, government agencies continued using Anthropic's tools as the White House and the company gradually mended ties ahead of Anthropic's planned IPO. Here is a timeline of the conflict:

Anthropic’s Pentagon blacklist struck down: How the conflict unfolded

Timeline of the conflict

Court blocks Pentagon blacklisting of Anthropic

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Date	Event
January 29	The Pentagon and Anthropic clash over eliminating safeguards that could allow the government to use its technology to target weapons autonomously and conduct U.S. domestic surveillance
February 23	U.S. Defense Secretary Pete Hegseth summons Anthropic CEO Dario Amodei to the Pentagon for talks on the military use of Claude
February 24	The Pentagon asks Anthropic to get on board, or risk consequences, including being labeled a supply-chain risk
February 25	The Pentagon asks defense contractors, including Boeing BA.N and Lockheed Martin LMT.N, to assess their reliance on Anthropic
February 26	Pentagon spokesperson Sean Parnell gives Anthropic a deadline to allow unrestricted military use of its technology until 5:01 p.m. ET on February 27
February 26	Anthropic refuses to eliminate safeguards from its AI systems