Sam Altman's new AI joint venture, Stargate, has drawn criticism from Elon Musk.Musk said on X that Stargate didn't have the funds to build AI infrastructure. Altman has responded.The exchange between the pair is another chapter in their long-running feud.Elon Musk took to X to post a jab at Sam Altman after President Donald Trump announced a new joint venture between Altman's OpenAI, SoftBank, and Oracle.On Tuesday, Trump announced Stargate, a $500 billion AI infrastructure investment project that would see the three companies join forces. Altman said Stargate will allow AGI, or artificial general intelligence, to be built in the US.Musk, however, thought otherwise."They don't actually have the money," Musk wrote in an X post on Tuesday night.Musk was responding to a post by OpenAI which said that the company will "begin deploying $100 billion immediately" as part of Stargate."SoftBank has well under $10B secured. I have that on good authority," Musk added in a subsequent post, without providing any evidence to support his claim.Altman: Musk is wrong about StargateAltman started off on Wednesday extending an olive branch to Musk."I genuinely respect your accomplishments and think you are the most inspiring entrepreneur of our time," Altman wrote in reply to Musk's post on Tuesday night.But, just over an hour after that post, Altman said in a separate post that he thought Musk was wrong about Stargate's financial capital. He also invited Musk to visit Stargate's first infrastructure site."I realize what is great for the country isn't always what's optimal for your companies, but in your new role I hope you'll mostly put America first," Altman wrote.Musk did not respond to Altman's comments head-on. Instead, the Tesla CEO shared an X post by Altman from December 2021, where Altman thanked LinkedIn cofounder Reid Hoffman for helping to stop Trump from being re-elected in 2020.Altman was at the Trump inauguration on January 20, and has struck a more conciliatory tone about the Trump administration. On Wednesday night, Altman said in an X post that he changed his mind on Trump after watching the president "more carefully recently.""I'm not going to agree with him on everything, but i think he will be incredible for the country in many ways!" Altman wrote on X.Musk and Altman did not respond to requests for comment from BI.Musk vs. AltmanMusk's and Altman tit-for-tat exchanges on Stargate aren't surprising, considering their tense relationship.Musk cofounded OpenAI with Altman back in 2015. He left OpenAI's board in 2018.Musk is now a vocal critic of the ChatGPT maker. He's also been working on his own AI ventures, both at Tesla and at his AI startup, xAI.In February, Musk filed a lawsuit against OpenAI, accusing it of violating its nonprofit mission by partnering with Microsoft. The lawsuit was withdrawn in June, but Musk re-filed it in August.In November, Musk's lawyers filed an injunction against OpenAI to stop its conversion into a for-profit entity. A spokesperson for OpenAI told Business Insider that Musk's injunction is "utterly without merit."Thus far, Altman has been largely diplomatic when commenting about Musk. This in spite of the nickname that Musk has given him: "Swindly Sam.""I don't think he's a nice person or treating us fairly but you have to respect the guy and he pushes all of us to be more ambitious," Altman wrote in an X post on Wednesday.