Questioning the effectiveness of the surveillance programme, a top investigative publication here has said the U.S. intelligence failed to track Mumbai attack convict David Headley and he was arrested only after a tip off was provided by the British intelligence.

“The government surveillance only caught up with Headley after the US had been tipped by British intelligence. And even that victory came after seven years in which US intelligence failed to stop Headley as he roamed the globe on missions for Islamic terror networks and Pakistan’s spy agency,” said ProPublica , an investigative publication.

National Intelligence Director James Clapper and Keith Alexander, commander of the US Cyber Commander and Director of the National Security Agency, have claimed that Headley was nabbed through this surveillance process.

“Supporters of the sweeping US surveillance effort say it’s needed to build a haystack of information in which to find a needle that will stop a terrorist. In Headley’s case, however, it appears the US was handed the needle first — and then deployed surveillance that led to the arrest and prosecution of Headley and other plotters,” ProPublica said. “As ProPublica has previously documented, Headley’s case shows an alarming litany of breakdowns in the US counterterror system that allowed him to play a central role in the massacre of 166 people in Mumbai, among them six Americans,” it said.

“The failure here is the failure to connect systems,” it quoted an official — PTI