Motherboard is citing former NSA staffers who are convinced another insider smuggled the weapons out of an air-gapped system, while The Intercept has definitively tied the malware to the NSA. Pretty much a worst-case scenario for the agency.
I certainly may not like how the NSA knowingly chooses to target Americans' data, but I agree without reservation with their mandate for digital intelligence-gathering against foreign actors. I don't want their methods exposed nor their digital nuclear weapons available to those enemies. I respect Snowden's responsible disclosure; this is reprehensible.