OpenAI is staggering the release of its latest AI model after a request from the US government, in a move echoing the launch of Anthropic’s Mythos product.

The company behind ChatGPT signalled its dissatisfaction with the move, saying that it keeps the best AI tools from “users, developers, enterprises, cyber defenders, and global partners who need them”.

OpenAI said on Friday it was launching its GPT 5.6 series with a “small group” of trusted partners.

“As part of our ongoing engagement with the U.S. government, we previewed our plans and the models’ capabilities ahead of today’s launch,” said OpenAI in a blog post. “At their request, we are starting with a limited preview for a small group of trusted partners whose participation has been shared with the government, before releasing more broadly.”

Anthropic, OpenAI’s close rival, had carried out a similar release programme for its Mythos model but has now pulled the technology entirely after the US government ordered the company to stop foreign nationals from accessing public versions of the model, which has powerful cyber-hacking capabilities. Anthropic had at first delayed the widespread release of Mythos voluntarily but OpenAI appears to have done so at the federal government’s behest.

Stating its disquiet with the US government approach, it said: “We don’t believe this kind of government access process should become the long-term default.”

However, the company said it believed taking this “short-term” step was the “strongest path to broader availability in the coming weeks” as it works with the White House to develop a vetting and deployment framework for new models, as required under an executive order issued by President Donald Trump.

In another parallel with Anthropic’s US government clash over Mythos, OpenAI said all the entities receiving access to GPT 5.6 will be US-based but it hopes to add foreign partners next week. However, employees of those companies given access who are based abroad in “supported countries” – which include the UK and Australia – will have access to the model.

GPT 5.6 is comprised of three versions: Sol, the strongest of the suite; Terra, which has slightly lower performance capabilities but is cheaper for users; and Luna, the lowest cost version.

OpenAI said GPT 5.6 Sol was its “strongest model yet” but did not cross a “cyber critical threshold” under its internal framework for measuring dangerous AI capabilities. It added that Sol was is “better at helping people find and fix vulnerabilities than reliably carrying out end-to-end attacks.”

OpenAI’s chief executive, Sam Altman, told staff this week the federal government had asked for a staggered release. He said the government would be “approving access customer by customer during this preview period” for GPT 5.6 and that it would be released more generally “a couple of weeks later” if the process went well.

“We’ve made clear to the US government that this is not our preferred long term model, and will work with them and others in industry to achieve a more sustainable approach for future releases,” Altman said in the memo, obtained by The Information.

OpenAI had been working with the US government over a preview of the model, which would be used to power OpenAI’s ChatGPT chatbot. The staggered release was requested after conversations with two government agencies: the Office of the National Cyber Director and the Office of Science and Technology Policy.

The Information reported that Trump’s commerce secretary, Howard Lutnick, had intervened against even a limited release, calling Altman to demand approvals from other agencies.

This month, the US president signed an executive order to create a voluntary framework for the federal government to vet powerful new AI models before they are released.

The order represents a shift from the White House’s previously deregulatory stance on AI. Last year, the vice-president, JD Vance, said “excessive regulation of the AI sector could kill a transformative industry”.

However, the White House’s stance has changed against a backdrop of rapidly improving model capabilities, including Mythos which has been described by the UK’s AI security body as a “step up” over previous cutting-edge models.