"We're still trying to figure out how you use things like Twitter as a source. How do you establish trends and how do you then capture that in an intelligence product?”, Wagner was quoted by the Associated Press as saying.

Wagner said that the department is developing protocols under strict privacy laws, including rules dictating the length of time the information can be stored and differences between domestic and international surveillance.

The challenge is to develop protocols for collecting and analyzing information so that it provides law enforcement officials with meaningful intelligence. "I can post anything on Facebook, is that valid? If 20 people are tweeting the same thing, then maybe that is valid. There are just a lot of questions that we are sort of struggling with because it's a newly emerging (issue)", she said.

The DHS official stressed that her department does not actively monitor social media sites, although documents obtained last year by the Electronic Frontier Foundation (EFF) indicated that the department had in fact snooped on social networking sites during the inauguration of President Obama.

According to documents obtained by EFF under the Freedom of Information Act, DHS set up a social networking monitoring center to collect and monitor online communication during the 2009 presidential inauguration, among other activities.