I meant more along the lines of mentioning the main organization of each game (like Rainbow, Ghost Recon, Third Echelon or HAWX).
Also, isn't it implied that the CIA generally doesn't have a good relationship with the NSA in the Splinter Cell universe? I don't see how or why a NSA sub-agency can be considered a CIA asset in that context. If the line had been "the NSA already had an asset in country" then I could see how that could be construed as a reference to Splinter Cell. But I don't think this is.