The White House said there may need to be additional constraints placed on America's spy agencies after a series of embarrassing disclosures about the broad scope of US intelligence gathering.
"We recognize there needs to be additional constraints on how we gather and use intelligence," said White House spokesman Jay Carney.
The White House has said its review of US intelligence-gathering procedures will be completed by the end of the year.
More top news
A suspected drug dealer led police in Texas on what may be one of the slowest car chases ever - taking two hours to travel just 17 miles.
Doctors cannot explain it but the extraordinary bond between new mum Holli Cheung and her son Jordan may have saved her life.
David Cameron has begun a whirlwind tour of Europe to discuss his terms for renegotiating the UK's membership of the EU with key leaders.