Anthropic’s Claude climbed to the No. 1 spot on Apple’s App Store over the weekend, dethroning ChatGPT just days after OpenAI CEO Sam Altman announced his company had supplanted Anthropic by striking a nine-figure deal with the U.S. Department of War.

Before the release of Anthropic’s Super Bowl ads—which took a dig at OpenAI’s move to include ads in ChatGPT—Anthropic was ranked 42nd on Apple’s App Store. Since then it has remained in the top 10 most downloaded apps, but OpenAI’s Pentagon contract may have helped push it into the top spot over the weekend. Claude stood at No. 5, compared with No. 2 for ChatGPT, on the Google Play store as of Monday.

ChatGPT users protested OpenAI’s Pentagon contract online in recent days by spreading the message to “Cancel ChatGPT” across Reddit and X. Some users posted guides for deleting ChatGPT accounts and migrating to Claude. Others accused OpenAI of opportunism, pointing out Altman had previously supported Anthropic’s stand, before signing the deal Anthropic rejected. 

As Claude seized the top spot, ChatGPT fell to second, and Google’s Gemini lagged behind in fourth place on the App Store. Since the start of the year, free active users on Claude have increased by over 60%, and daily sign-ups have quadrupled. 

Claude’s rise comes after the public fallout between Anthropic and the Pentagon over how AI technology can be used by the military. Defense Secretary Pete Hegseth warned Anthropic CEO Dario Amodei that if the company refused to allow its AI models to be deployed for “all lawful purposes,” including potential applications in surveillance and fully autonomous weapons, the Pentagon would terminate its contract and label Anthropic a national security risk. Amodei rejected the terms outright. 

“Threats do not change our position: We cannot in good conscience accede to their request,” Amodei said in a statement.

Following Amodei’s refusal, President Donald Trump hit back in a post on Truth Social, calling it a “Radical Left AI company,” and ordered every federal agency to phase out Anthropic’s technology within six months. Hegseth later said in a post on X that he was designating the company a “supply-chain risk to national security,” a label usually applied to firms with ties to foreign adversaries. 

Hours later, and despite his initial alignment with Anthropic’s Amodei, Altman announced OpenAI had reached its own agreement with the Pentagon to deploy the company’s models on its classified network. 

Altman argued in a post on X that OpenAI’s deal includes the same core safety guardrails Anthropic had demanded, including a prohibition on using the tech for domestic mass surveillance and requiring human responsibility for use of force, such as autonomous weapon deployment. As part of the agreement, OpenAI placed limitations barring the use of its AI for purposes that go against its redlines, Altman said.

“The DOW agrees with these principles, reflects them in law and policy, and we put them into our agreement,” Altman wrote in the post.

OpenAI did not immediately respond to Fortune’s request for comment.

Over the weekend, Altman defended the AI company’s decision to strike a deal with the Pentagon, writing that it will build a system that the Department of War can use in “laws and directives around autonomous weapons and surveillance.”

“But we get to decide what system to build, and the DOW understands that there are lot of risks we deeply understand. We can, and will, build a lot of protections into that system, including for ensuring that the redlines are not crossed,” he wrote. 

Amodei, for his part, called the government’s designation “retaliatory and punitive” in an interview with CBS News. He added that Anthropic is still open to working with the military within its previously stated limits, but that it drew its redlines because “we believe that crossing those lines is contrary to American values, and we wanted to stand up for American values.”