President Barack Obama is ordering changes to the US government's vast collection of phone records and promising that "we will not monitor the communications of heads of state and government of our close friends and allies".
He said he will end the programme "as it currently exists".
Mr Obama's highly anticipated speech said intelligence heads didn't intentionally abuse the programme to invade privacy.
But Mr Obama (left) also said he believes critics of the programme have been right to argue that without proper safeguards, the collection could be used to obtain more information about Americans' private lives.
He also sought to reassure allies and others overseas.
"The bottom line is that people around the world – regardless of their nationality – should know that the United States is not spying on ordinary people who don't threaten our national security, and that we take their privacy concerns into account," he said. "The leaders of our close friends and allies deserve to know that if I want to learn what they think about an issue, I will pick up the phone and call them, rather than turning to surveillance."