Microsoft has laid off over 15,000 employees this year, but CEO Satya Nadella says headcount "is relatively unchanged" as the company continues to hire new workers. In a memo to staff on Thursday morning, released publicly on Microsoft's corporate blog, Microsoft CEO Satya Nadella addressed the recent job cuts, calling the decisions some of "the most difficult" that he had to make. He noted that headcount at Microsoft "is relatively unchanged" as the company continues to hire new workers, and he doesn't promise that there won't be more layoffs in the future. Microsoft CEO Satya Nadella. Photographer: Chona Kasinger/Bloomberg via Getty ImagesIn the memo, Nadella also redefined Microsoft's mission from a "software factory" to an "intelligence engine."