US would probably have a large impact as well, of course because lots of internet-users are from the US, but also because the US likes to astroturf as well.
tiny example: https://web.archive.org/web/20160406094911/http://www.reddit..., Most addicted city (over 100k visits total) Eglin Air Force Base, FL
let's not lose ourselves in cold-war propaganda too much and act like russians and chinese are the only ones astroturfing online.