Google had spent the previous months building a closer relationship with the US Defense Department after a few frosty years. In 2018, more than 4,000 Googlers sent a letter imploring Pichai to cancel Project Maven, a contract that used Google's AI to analyze drone footage. Google chose not to renew the contract, and drew up a set of company-wide principles that included a pledge not to use its AI for military or surveillance. The language in the two employee letters — sent eight years apart —