US Secretary of State John Kerry said for the first time Thursday that in some cases, US spying has gone too far, amid a row with Europe over the matter.
"I assure you, innocent people are not being abused in this process, but there's an effort to try to gather information," Kerry told a London conference via video link. "And yes, in some cases, it has reached too far inappropriately."
"And the president, our president, is determined to try to clarify and make clear for people, and is now doing a thorough review in order that nobody will have the sense of abuse," he said.
"And in some cases, I acknowledge to you, as has the president, that some of these actions have reached too far, and we are going to make sure that does not happen in the future."
Recent allegations and reports of widespread spying by the National Security Agency have sparked a major rift in trans-Atlantic ties.
Just last week, German Chancellor Angela Merkel angrily confronted US President Barack Obama with allegations that the NSA was snooping on her phone, saying it would amount to a "breach of trust."
A German intelligence delegation and a separate group of EU lawmakers were in the US capital Wednesday to confront their American allies about the alleged bugging.
Kerry's remarks — released in a State Department transcript — came in response to a question addressed to both him and British Foreign Secretary William Hague about government surveillance.
The top US diplomat spent a good portion of his answer justifying the collection of data as necessary due to the threat of terrorism.
"Many, many, many parts of the world have been subject to these terrorist attacks," he said.
"And in response to them, the United States and others came together — others, I emphasize to you — and realized that we're dealing in a new world where people are willing to blow themselves up."
He added: "We have actually prevented airplanes from going down, buildings from being blown up, and people from being assassinated because we've been able to learn ahead of time of the plans."