President Obama tries to calm fears over Prism programme that mines private data from Google, Apple, YouTube and Facebook

Central servers of nine leading US internet companies are accessed in Prism programme

Google, Facebook, Apple and YouTube have all had their data targeted by the NSA

Barack Obama has defended the US government’s previously undisclosed eavesdropping operations put in place in the years since the 9/11 terrorist attacks and dismissed reporting of them as “hype”.

“No one is listening to your phone calls,” Obama insisted, taking a break from his planned schedule while visiting California to address the fast-growing controversy.

“The people who are involved in America’s national security, they take this work very seriously; they cherish our constitution.”

The White House and the agencies directly involved, notably the National Security Agency, NSA, are trying to keep up with leaks about two programmes: one that sweeps up details of US calls handled by phone giant Verizon and another that monitors foreigners’ data such as emails, photos and chats flowing through the servers of internet firms like Apple, Google and Microsoft, using a programme known as Prism.

Obama dismissed some of the reporting of these programmes as “hype” and sought cover from the fact that all of them had been authorised by Congress. The revelations are bound to trigger a new debate in Washington about the presumption of privacy in America and if it exists any more. It also comes at a tricky time for Mr Obama who is already dealing with other stumbles including the undisclosed gathering of phone records of journalists covering security affairs.

Mr Obama said he welcomed debate on “balancing the need to keep the American people safe and our concerns about privacy, because there are some trade-offs involved”. But he added: “You can’t have a hundred per cent security and also then have a hundred privacy and zero inconvenience.”

The head of the publicity-averse NSA, James Clapper, took the unusual step of declassifying some of the details of the phone-data programme that monitors the calls of millions of Americans under order from a special Foreign Intelligence Service or FISA Court. In a statement he scolded: “The unauthorised disclosure of information about this important and entirely legal program is reprehensible.”

Mr Clapper spoke of “numerous inaccuracies” in the reporting of the internet oversight programme, PRISM, which seeks out terror leads in places such as social network sites. “It cannot be used to intentionally target any US citizen, any other US person, or anyone located within the United States,” he said.

Senator Rand Paul, a hero of the Tea Party and libertarian wing of the Republican Party called the accessing of Verizon telephone data “an astounding assault on the Constitution”, and vowed to table legislation to rein in the NSA. But others were more sanguine.

“If you’re not getting a call from a terrorist organisation, you got nothing to worry about,” said Republican Sen. Lindsey Graham.

Further reading:

GCHQ handed personal web data by US spies
Prism and the US internet giants: The relationship and the numbers
Q&A: What is Prism, is it legal and what data can it obtain?