DNI Clapper said the U.S. government has not made an official statement regarding attribution for China and OPM because all “three types of evidence” are missing, or do we have one, or perhaps two? If that is the case, which elements do not have, and not have? How specific is the “actual perpetrator doing the keystrokes”? Did he require the Intelligence Community to identify a named person, such that the IC knows the responsible team? Contrast the OPM case with the DPRK hack against Sony.”]
Source: https://taosecurity.blogspot.com/2015/09/attribution-opm-vs-sony.html