Some forces in the US don't want good relations with Russia. Thats all. Russians has many clever hackers so there's no need to send them to US, to get the secrets in many cases. And the second, nowadays spies use far more clever techniques as the officials talking about. It's as hollow as B quality hollywood movie.

Technology which is already here for a long time has now a buzzword - SNARE. For example OpenBSD spamd doing the same based on blacklists, greylists and even on Operating System fingerprints. Wheel is reinvented again... ;-)