The military has long had control over US mass media. Since before WW II it has had employees that work directly in media, they create fake stories and make sure that most American and a lot of foreign media serve the needs of the war industry. Only reporters who are willing to play the game are allowed access to military operations. Even pseudo-liberal media such as National Public Radio and TV has long been a psy-op and under the direct control of the military. Truly independent media is rarely tolerated.
The military has been quick to utilize the Internet and social media as well. When the Internet first got started services such as Compuserve and AOL were instruments of military intelligence and various operations were run through them. The Air Force's OSI actually ran the "Encounters Forum" and "Abductee Support Group" on Compuserve back in the mid 90's to identify authentic alien experiencers so that the military could abduct them and program them to spy for the military during their next 'encounter'. The various Sys-Ops on the forum were actually intelligence agents using multiple fake identities. They also ran numerous other fake personalities to befriend targeted people and had real agents embedded in the online communities to befriend targets and take relationships to the next level in the physical world. I know because I was targeted and was the one responsible for exposing the operation and shutting down the Encounters Forum. They tried to restart it as a new age forum but were never able to win the trust of the original group of 'experiencers'.
Newer social media such as Facebook and MySpace are heavily infested with spooks and a massive army of fake personas to shape public opinion and attack opponents. Every major Internet service has deep connections to US and Israeli intelligence agencies. Even some very low-brow anti-govt. sites that one would never suspect are actually military intelligence operations designed to attract, profile and track thinking people who might pose a threat in the future.
For more info. on the topic you might want to read some of the articles that paint a partial picture of the issue: