US intelligence on defensive over data programmes

Top US intelligence officials say that information gleaned from two controversial data-collection programmes run by the National Security Agency thwarted potential terrorist plots in the US and more than 20 other countries — and that gathered data is destroyed every five years.

Last year, fewer than 300 phone numbers were checked against the database of millions of US phone records gathered daily by the NSA in one of the programmes, the intelligence officials said in arguing that the programmes are far less sweeping than their detractors allege.

Intelligence officials said they are working to declassify the dozens of plots NSA chief Gen Keith Alexander said were disrupted, to show Americans the value of the programmes, but that they want to make sure they don’t inadvertently reveal parts of the US counter-terrorism playbook in the process.