
I did.  You're mistaken.  NSA's communications intelligence mission is
strictly against foreign governments.  Here's an excerpt from the enabling
charter (24 Oct 52, Truman) that should clarify this.  The charter was
declassified in about Feb 1990 when an FOIA request made it public.  Mind
you, I don't know that they never collect anything they're not supposed
to... but spying on US citizens isn't in their charter.

    b. The COMINT  mission of the National  Security Agency
	(NSA) shall be to provide an effective,  unified organization
	and control of the communications  intelligence activities of
	the United States  conducted against foreign  governments, to
	provide for  integrated operational  policies and  procedures
	pertaining thereto.   As  used in  this directive,  the terms
	"communications intelligence"  or "COMINT" shall be construed
	to mean all  procedures and methods used in  the interception
	of communications  other  than foreign  press and  propaganda
	broadcasts  and  the  obtaining  of   information  from  such
	communications by other  than intended recipients,  but shall
	exclude censorship  and the  production and dissemination  of
	finished intelligence.

They're also tasked with protecting the US's communications, but I haven't
seen the specific enabling memo on that.  I assume that's the role under
which Skipjack was developed.

NSA is not in the standard-setting business, though -- that's why this
Clipper stuff came from NIST, which I believe is tasked with coming up
with standards based on their best inputs from other government agencies,
which would include NSA.