I don't know where they operate out of, but they work globally, using networks around the work and special software to coordinate their postings and tag-team attacks in social media.

https://www.theguardian.com/technology/2011/mar/17/us-spy-operation-social-networks
https://www.theguardian.com/commentisfree/cifamerica/2011/mar/17/us-internet-morals-clumsy-spammer
http://www.reuters.com/article/us-election-intelligence-commentary-idUSKCN10F1H5
http://www.businessinsider.com/ndaa-legalizes-propaganda-2012-5
https://consortiumnews.com/2017/03/25/how-us-flooded-the-world-with-psyops/

“The CENTCOM contract stipulates that each fake online persona must have a convincing background, history and supporting details.”

… “the software could allow US service personnel, working around the clock in one location, to respond to emerging online conversations with any number of co-ordinated messages, blogposts, chatroom posts and other interventions.”