Interesting analysis on why the NSA is absent from the FBI-Apple fight: theintercept.com/2... I'd be willing to bet the NSA can break the phone but wants the FBI to be allowed to push through a legal precedent
To be fair, the NSA isn't really allowed to take action in such a clearly federal case. The whole spying-on-all-Americans is borderline on their SIGINT mission statement, cracking a physical phone for police action is definitely outside of it. Maybe the NSA is sticking to the law this time around?!