OpenAI has started previewing its GPT‑5.6 series, which will be available in three versions, to a limited number of trusted partners. The company says the variant Sol is its strongest model yet, while Terra is for everyday use and has a similar performance to GPT‑5.5 despite being twice as cheap. Luna, the last variant, is the company’s lowest cost model. OpenAI plans to give them a broad release sometime in the coming weeks.

The company gave the US government a preview of GPT‑5.6 and its capabilities before today. It’s also  by the administration’s request that it is previewing the model to a small group of trusted partners “whose participation has been shared” with the government. “We don’t believe this kind of government access process should become the long-term default,” OpenAI wrote in its announcement. It said it’s taking the “short-term step,” for now, because it ensures it can release its latest model series to the public soon. 

President Trump signed an AI cybersecurity order earlier this month, which asks companies to present their most powerful models for voluntary government review 30 days before making them publicly available. According to a recent report by The New York Times, OpenAI, Anthropic, Google, xAI and Microsoft have been giving the government early access to their latest models even before Trump signed the order. Meta was the only holdout, and the US government has reportedly been urging it to submit its AI models for evaluation. 

GPT‑5.6 introduces a “max” reasoning effort, which gives Sol more time to reason deeply. Sol is also OpenAI’s most capable model for cybersecurity and is the best option to help users find and fix vulnerabilities. OpenAI says Sol comes with strengthened protections for high-risk activities and sensitive requests. It also says that the company had spent several weeks finding its weaknesses and fortifying it against real-world attacks.

The company put safeguards on all the variants, however, to make sure they hold up to real adversarial pressure. In addition, OpenAI trained GPT-5.6 to refuse “prohibited cyber assistance,” including attempts at jailbreaking the model. It spent 700,000 GPU hours to find universal jailbreaks to develop measures against them, and it pledges to implement a “rapid-response process to reproduce, assess, prioritize, and remediate newly discovered jailbreaks.”

OpenAI’s focus on jailbreak prevention likely stems from what happened to Anthropic. A couple of weeks ago, Anthropic suspended all access to its Mythos 5 and Fable 5 models after a directive from the government. While the company didn’t say it outright, Amazon and other companies had reportedly notified authorities that its models could be jailbroken and used for malicious purposes. It has started lifting its access block, though, since US government has just given Anthropic permission to redeploy Mythos to a select group of organizations. 

The company has priced GPT‑5.6 Sol at $5 per million input tokens and $30 per million output, much less than what Fable cost when it was still available. ($10 for input and $50 for output for the same amount of tokens.) Terra costs $2.50 for input and $15 for output, while Luna costs $1 for input and $6 for output.