Re: UFP & Cloaking devices (post-singular destiny with spoilers)
^It seems that they already have. As I stated earlier, in Resistance we find out that Starfleet has schematics for cloaking devices implanted in each ships computer core, and is available with an Admiral's say-so...
But until now, if an Admiral did authorize it, they'd be court-martialed for provoking conflict with the RSE by violating treaty...
"Your powers are useless on me, you silly billy".