U.S. lawmakers are concerned about Microsoft's $1.5 billion investment in UAE-based AI firm G42 due to potential national security risks and the company's historic ties to China. They request an intelligence briefing before the deal proceeds to the second phase, which involves the transfer of export-restricted semiconductor chips and model weights. Lawmakers highlight the lack of regulations around sensitive AI model exports and fear that companies like G42 might share the technology with U.S. adversaries, such as China.