Is NSA surveillance really necessary to defend against terrorist attacks? It's been a common claim by the agency's defenders as the programs come under scrutiny, but a report released today by the New America Foundation casts doubt on that logic. The report examines how NSA surveillance functioned in 225 counterterrorism cases since 9/11 and concludes that the agency wasn't as crucial as it would have you believe.

The report found that the NSA was responsible for 7.5 percent of counterterrorism investigations, and there was only one case out of the 225 that was initiated by NSA evidence. The case involved a cab driver named Basaaly Moalin who was convicted of sending money to Somalian terrorist groups. While successful, the case did not involve any direct threat of attack, and took more than two months between the initial tip and the eventual action by the FBI. Far more common were cases initiated by traditional tools like informants or suspicious-activity reports, which helped law enforcement focus their attention on particular targets. "The overall problem for US counterterrorism officials is not that they need vaster amounts of information from the bulk surveillance programs," the report says, "but that they don’t sufficiently understand or widely share the information they already possess."