A non-nation state actor -- not the Russian government -- may have been behind the recent internet attack that crippled many popular sites across U.S., according to the man who oversees U.S. intelligence agencies.
"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," Director of National Intelligence James Clapper said on Tuesday during a live-streamed discussion organized by the Council on Foreign Relations.
The Oct. 21 attack hit the company known as Dyn, whose servers monitor and reroute internet traffic. Company officials said the firm began experiencing what security experts called a distributed denial-of-service attack just after 7 a.m. on the East Coast that spread across the country throughout the day, The New York Times reported.
It has not been determined if a nation state was supporting the non-state hacker in the massive internet attack, Clapper said.
Earlier this month, the U.S. formally blamed the Russian government for cyberattacks on the Democratic National Committee and the Democratic Congressional Campaign Committee.
The issue of cyberattacks has also become a flashpoint in the presidential election between Republican presidential candidate Donald Trump and his Democratic opponent Hillary Clinton.
During the second debate, Clinton said "cyberwarfare will be one of the biggest challenges facing the next president." While some hackers do it for commercial gain, "increasingly we are seeing cyberattacks coming from states, organs of states, the most recent and troubling of these has been Russia."
Trump said he agreed with "parts" of Clinton's statements but questioned whether Russia was behind recent hacking of the political group. "We should be better than anybody else and perhaps we're not," he said during the forum.
Clapper would not discuss the issue beyond the formal statement that his office released.
"I believe our statement said that 'it goes to the highest levels of the Russian government,' " he said.
The White House is considering retaliatory measures, but Clapper cautioned that a cyberattack against Russia would likely cause it to respond in kind.
"The risk is given the tremendous dependence of this nation on the cyber domain to do everything … we have to think twice and be very cautious about retaliating in a cyber context," he said.