President Barack Obama is urging Americans to "make some choices" in balancing privacy and security as he defends once-secret surveillance programs that sweep up an estimated 3 billion phone calls a day and amass Internet data from U.S. providers in an attempt to thwart terror attacks, AP reported.

Obama says it will be harder to detect threats against the U.S. now that the two top-secret tools to target terrorists have been so thoroughly publicized.

At turns defensive and defiant while speaking to reporters on Friday, June 7, Obama stood by the spy programs revealed this week.

The National Security Agency has been collecting the phone records of hundreds of millions of Americans each day, creating a database through which it can learn whether terror suspects have been in contact with people in the U.S. It also was disclosed this week that the NSA has been gathering all Internet usage, audio, video, photographs, emails and searches from nine major U.S. Internet providers, including Microsoft and Google, in hopes of detecting suspicious behavior that begins overseas.

"Nobody is listening to your telephone calls," Obama assured the nation after two days of reports that many found unsettling. What the government is doing, he said, is digesting phone numbers and the durations of calls, seeking links that might "identify potential leads with respect to folks who might engage in terrorism."