Chugalug2,
The former and I'm afraid that when viewed across Defence, they have a huge amount of sway as they are the ones holding the purse strings so to speak.
In the current climate of persistent doctrinal austerity, it's J8 who will decide whether a plan or capability is affordable, regardless of the actual operational imperative, and I have spent more time writing business cases just so people can do the jobs they are in post for than I would ever care to remember.