US director of national intelligence James Clapper told the US media the massive data collection program carried out by his government's National Security Agency (NSA), played a major roll in thwarting the planned 2010 terrorist attack against Jyllands-Posten newspaper’s Copenhagen offices.  

Clapper said that information collected by the Prism programme led authorities to international terrorist David Coleman Headley, who admitted to taking part in a plot, along with co-conspirator Canadian-Pakistani businessman Tahawwur Rana, to attack Jyllands-Posten’s offices in Copenhagen and Aarhus and behead employees and throw their heads into the street.

The plot was in response to the newspaper's publishing of cartoons of the prophet Mohammed, which led to protests around the world and hatched various terrorist retribution plots.

Clapper’s argument was greeted with skepticism in many quarters. German chancellor Angela Merkel demanded an explanation as to why the US is monitoring the whereabouts of EU residents that use platforms like Facebook and Gmail.

US senator and chairperson of the Senate Intelligence Committee Diane Feinstein said it was another program – not Prism – that led intelligence officers to Headly.

Others questioned the veracity of the claim that Prism was needed to track Headly, who was already well-known to US authorities as an informant for the US Drug Enforcement Agency (DEA).

Headly was sentenced to 35 years in a US federal prison for his key role in plotting the deadly 2008 Mumbai terrorist attack. He admitted to his involvement in the Jyllands-Posten plot during his trial.

Whistleblower Edward Snowden unveilled details of NSA’s Prism program in interviews last week. Snowden released documents that revealed that NSA has stockpiled information on the internet and telephone use of millions of people around the world.