It's not just Facebook who's interested in studying your status updates. The Pentagon, it turns out, has been studying social media use with a series of research projects reminiscent of Facebook's controversial emotion manipulation study for years.

Some of these programs, described in a Guardian report on Tuesday, were funded by the Pentagon's cutting-edge research arm, the Defense Advanced Research Projects Agency (DARPA), mostly known for far-out ideas such as mind-controlled robotic arms, dystopian-looking war robots and laser weapons worth of Star Trek or Star Wars,

Some of the projects detailed in the Guardian report sound relatively innocuous — even silly — such as the analysis of Tweets by celebrities including Lady Gaga and Justin Beiber as well as tracking the spread of memes online.

Others, however, could prove more controversial, such as studies that examined the online behavior of Occupy protesters and Middle East residents. DARPA has spent more than $15 million dollars funding these research projects, according to the Guardian.

The projects are part of DARPA's Social Media in Strategic Communication (SMISC) program launched in 2011 to study "linguistic cues, patterns of information flow and detection of sentiment or opinion in information generated and spread through social media," according to the program's website. (The Guardian and others have previously reported on the existence of this program.)

There's no evidence that any of the research sponsored by DARPA violated ethical rules or tried to manipulate social media users, though some studies definitely sound creepy.

A study by Georgia tech researchers titled "Cues to Deception in Social Media Communications" concluded that social media networks are good tools for spreading false information through deceptive breaking news updates. The study was not conducted by manipulating Facebook's News Feeds, but with volunteers using a fake social network called "FaceFriend." But it's easy to see how influencing real social media use might be useful for the U.S. government or its allies.

British spies from the Joint Threat Research Intelligence Group (JTRIG) are interested in "propaganda," "deception," and "pushing stories" online as recently revealed in documents leaked to journalists by Edward Snowden. And the infamous Cuban Twitter project to undermine Raul Castro's regime suggests that the U.S. might not just be interested in tracking what people talk about online but also take advantage of social networks to influence how they think and act.

In another instance, researchers tried to "actively identify and engage the right strangers at the right time on social media to help effectively propagate intended information within a desired time frame," according to the abstract of the study titled "Who Will Retweet This? Automatically Identifying and Engaging Strangers on Twitter to Spread Information."