Microsoft has deployed GPT-4, a large language model, in an isolated, air-gapped Azure Government Top Secret cloud for use by the Department of Defense. Once accredited, Pentagon officials will be able to use the technology in a secure environment. The tool is expected to help DOD officials deal with vast amounts of data and simplify information sorting. Microsoft is a major investor in OpenAI, the maker of GPT-4 and the popular ChatGPT.