Civil Liberties a 'Thorny Policy Challenge' While Thwarting US Terror

— -- The White House acknowledged today that tracking Americans inspired by ISIS propaganda, and thwarting potential attacks, without compromising civil liberties is “among the most difficult challenges that the president faces.”

The comment comes the same day the head of the FBI’s counter-terrorism division told Congress "we are dark" when it comes to tracking some private communications of suspected terrorists because of advanced encryption by mobile companies.

“This is a very thorny policy challenge and maybe even among the most difficult challenges that the president faces, but it's one that he's mindful of,” White House Press Secretary Josh Earnest told ABC News’ Jonathan Karl in today’s press briefing.

“The president himself has even observed on previous occasions that the threat that he's particularly worried about is sort of the lone wolf threat -- an individual that could be radicalized -- but essentially would carry out an operation of their own doing that would result in some violence,” Earnest said. “And trying to prevent that is exceedingly difficult.”

Earnest suggested the president would like to coordinate more closely with the technology sector in gaining access to information that can be useful in thwarting the threat posed by radicalized actors.

“There is an opportunity for us, in the mind of the president, to work with the tech sector on this, that as much as they value and champion the privacy and civil liberties rights of American citizens, we also know that those individuals do not want to be in a situation where their technology is responsible for allowing somebody who is seeking to carry out an act of violence to evade detection from the federal government,” he said, acknowledging that there is a challenge when it comes to balancing civil liberty concerns.

“This does set up a tough challenge of balancing the privacy and civil liberties of law-abiding American citizens with the need for us to try to detect and apprehend terrorists before they commit an act of violence,” he said.

The other challenge, Earnest said, is for law enforcement to stay on top of constantly evolving advances in technology.

"When we're talking about technology, we're talking about new innovations," Earnest said. "And it means that the techniques that are employed by the -- our national security professionals need to adapt to the innovations in the technology sector. And that is a very difficult challenge, but it's one that is -- that the president's team is very focused on."