OpenAI Launches GPT-5.6 Sol, Terra, and Luna in Limited Preview

OpenAI today launched a limited preview of its GPT–5.6 series, which includes flagship model Sol, a balanced everyday work model named Terra, and Luna, a fast and affordable model.

Terra is similar in performance to GPT–5.5 but it is 2x cheaper, and Luna offers "strong capability" at OpenAI's lowest price. GPT–5.6 Sol is OpenAI's strongest model to date, with agentic improvements in coding, biology, and cybersecurity. There is a new "max" reasoning effort and an "ultra" mode that uses sub-agents for complex work.

OpenAI says GPT–5.6 Sol has its most "robust safety stack to date" with protections for high-risk activity, sensitive cyber requests, and misuse. It has been tested for weaknesses and hardened against real-world attacks. OpenAI says safeguards allow the model to deliver "substantial benefit for legitimate defensive work" while limiting prohibited offensive use. It is better at helping users find and fix vulnerabilities than carrying out end-to-end attacks, according to OpenAI.

The Trump administration is limiting the launch of GPT–5.6, and OpenAI agreed to hold back on releasing it to all users. The model is instead available for a small group of trusted partners at the current time, but OpenAI is planning for a wider launch after further testing. In its GPT–5.6 announcement, OpenAI pushed back against the administration's request to hold the model back and said the government AI access process should not become the long-term default.

We don't believe this kind of government access process should become the long-term default. It keeps the best tools from users, developers, enterprises, cyber defenders, and global partners who need them. We are taking this short-term step because we believe it is the strongest path to broader availability in the coming weeks, while we work with the Administration to develop the cyber Executive Order framework and a repeatable process for future model releases.

The Trump administration is putting together a process for benchmarking and assessing new AI models prior to launch, per a June 2 executive order. The administration previously forced Anthropic to remove access to Claude Fable 5 and Mythos 5, even though Anthropic adhered to a voluntary government review process and added guardrails based on government feedback.

The GPT–5.6 models are available through the API and Codex to a trusted set of OpenAI partners and organizations. OpenAI says they will be available more broadly in ChatGPT, Codex, and the API "soon."

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