OpenAI launched GPT-5.6, its most powerful model to date, on July 9, sparking a social media feud between xAI CEO Elon Musk and OpenAI CEO Sam Altman. Musk accused Altman of "taking fraud to a whole new level," posting a screenshot of Altman saying "I do this because I love it" and commenting "By 'this' he means fraud." Altman responded by mocking Musk's "space data center" project, then posted that "Many benchmarks show 5.6 Sol is the world's most powerful model, but the clearest indicator is this: Elon is obsessed with me again." Musk retorted with a test flight invitation and accused OpenAI of betraying its mission: "First you steal an open-source AI charity, then you steal Apple phone technology!" The GPT-5.6 model is offered in three tiers: the flagship "Sol," sub-flagship "Terra," and cost-effective "Luna," and is capable of rivaling Anthropic's "Fable 5" model.