In a speech at the International Conference on Cyber Security (ICCS) today in New York, FBI Director James Comey reiterated the bureau’s confidence that North Korea was involved in the cyber attack on Sony Pictures Entertainment. “There’s not much I have high confidence about,” Comey said, as reported by the FBI New York field office’s official Twitter feed. “I have very high confidence… on North Korea.” And he downplayed suggestions by outsiders that others might be responsible, saying that critics “don’t have the facts that I have, they don’t see what I see.”

In a separate speech today at the ICCS, Director of National Intelligence James Clapper said that the attack on Sony demonstrated a new type of threat posed by North Korea. During a meeting last year with a North Korean general to negotiate the release of two American prisoners in North Korea, Clapper said that the general told him the regime is “deadly serious” about perceived insults by the US to its “supreme leader” and that North Koreans feel that the US has put their country under siege.

While the Sony attackers had largely concealed their identity by using proxy servers, Comey said that on several occasions they “got sloppy” and connected directly, revealing their own IP address. It was those slip-ups, he said, that provided evidence linking North Korea to the attack on Sony’s network. Comey also said that analysts at the FBI found the patterns of writing and other identifying data from the attack matched previous attacks attributed to North Korea. Additionally, there was other evidence, Comey said, that he could not share publicly.