Twitter is used heavily by the CIA and other intel outfits inside and outside the US. The CIA mentions it in a speech at Cornell and it's on their own website. The speech is interesting and was probably a sales pitch for new recruits. The Ivy League is a favorite recruiting ground for that three-letter-agency. See: https://www.cia.gov/news-information/speeches-testimony/2015-speeches-testimony/deputy-director-cohen-delivers-remarks-on-cia-of-the-future-at-cornell-university.html That was five years ago so I expect if anything they pay more attention nowadays. Apparently some well-known non-US intel agencies communicate via Twitter. I have never used it for several reasons but mainly because of its bias.