The announcement that Juniper found "unauthorized code" and it appears that the only entities which would benefit from the breach would be those like the NSA. Apparently the NSA and/or other similar entities have done something like this before, so it's likely the NSA or a counterpart is responsible for this breach.
Nobody can assure me that this is happened by chance. People are not so stupid. Yes, NSA is responsible for breaking into the Juniper Networks firewall. Somebody needed some kind of information. Somebody smart, did the work. Congratulate NSA but at the same time NSA did something very unethical,very wrong.
I see this kind of thing in tech companies all the time. By laziness or stupidity, Juniper left a backdoor open in their network and hackers exploited it. By blaming the NSA it looks like "there was nothing they could do" and everyone gets to keep their jobs, and the stock doesn't drop.
It is my belief that Juniper Networks is trying to benefit from the publicity that would be gained by an alleged NSA/rights violation scandal. I think that if the government was trying to monitor Juniper Networks then they would have made it known and gone about it in a legitimate fashion. It is probably a third party (i.e. not a nation-state) that is responsible.