When asked if the attack was perpetrated by a non-state actor, Clapper replied, "Yes, but I wouldn't want to be conclusively definitive about that yet," adding, "that's an early call."
“The investigation is still going on; there is a lot of data that we have gathered here, but that appears to be preliminarily the case,” Clapper said on Tuesday at an event for the Council on Foreign Relations.
"We've had this disparity or contrast between the capability of the most sophisticated cyber actors, nation-state cyber actors, which are clearly Russia and China, but have to this point perhaps more benign intent," Clapper said. "And then you have other countries who have a more nefarious intent. And then even more nefarious are non-nation-state actors," he added.
An entity calling itself the New World Hackers has claimed credit for the attack. It also took credit for another large DDoS attack on the BBC last year.