President Trump ordered the U.S. government to stop using the artificial intelligence company Anthropic's products and the Pentagon moved to designate the company a national security risk on Friday, in a sharp escalation of a high-stakes fight over the military's use of AI.

The twin decisions cap an acrimonious dispute between Anthropic and the Pentagon over whether the company could prohibit its tools from being used in mass surveillance of American citizens or to power autonomous weapon systems, as part of a military contract worth up to $200 million.

"The Leftwing nut jobs at Anthropic have made a DISASTROUS MISTAKE trying to STRONG-ARM the Department of War, and force them to obey their Terms of Service instead of our Constitution," Trump wrote in a Truth Social post. "Therefore, I am directing EVERY Federal Agency in the United States Government to IMMEDIATELY CEASE all use of Anthropic's technology. We don't need it, we don't want it, and will not do business with them again!"

He said there would be a six-month phaseout of Anthropic's products.

Trump's announcement came about an hour before a deadline set by the Pentagon, which had called on Anthropic to back down. Shortly after the deadline passed, Defense Secretary Pete Hegseth said he was labeling Anthropic a supply chain risk to national security, blacklisting it from working with the U.S. military or contractors.

"In conjunction with the President's directive for the Federal Government to cease all use of Anthropic's technology, I am directing the Department of War to designate Anthropic a Supply-Chain Risk to National Security. Effective immediately, no contractor, supplier, or partner that does business with the United States military may conduct any commercial activity with Anthropic," Hegseth posted on X , using the Pentagon's "Department of War" rebranding. "Anthropic will continue to provide the Department of War its services for a period of no more than six months to allow for a seamless transition to a better and more patriotic service."

Anthropic said it would challenge the supply chain risk designation in court.

"We believe this designation would both be legally unsound and set a dangerous precedent for any American company that negotiates with the government," the company said in a statement on Friday evening.

Anthropic also challenged Hegseth's comments that anyone who does business with the U.S. military would have to cut off all business with Anthropic. "The Secretary does not have the statutory authority to back up this statement," the company said. Under federal law, it said, designating Anthropic a supply chain risk would only apply to "the use of Claude as part of Department of War contracts—it cannot affect how contractors use Claude to serve other customers."

The company said it had "tried in good faith" to reach an agreement with the Pentagon over months of negotiations, "making clear that we support all lawful uses of AI for national security aside from the two narrow exceptions" being disputed. "To the best of our knowledge, these exceptions have not affected a single government mission to date," Anthropic said.