Officials attributed the ground stop to a telecommunications outage with no indication of a cyberattack as of November 13, though investigators had not determined the root cause. Law enforcement sources told CNN preliminary indications pointed away from a cyberattack, and the FAA lacked evidence linking it to a nefarious attack. The 2% reflects the low base rate for such incidents being confirmed as cyberattacks within 48 days, absent any affirmative evidence pointing toward that conclusion.