I'm glad one of these countries is thinking!
Project Pluto is a ramjet, needs air to function. Only benefit over conventional hydrocarbon fueled engine/ramjet is greatly increased loiter time.
To my knowledge the only proposed "nuclear rocket" idea capable of achieving orbit or beyond would be project Orion:
http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29
It throws out coke can sized nuclear bombs underneath itself in quick succession, that thing would win any dick waving competition hands down!
The wikipedia article was polite and non-alarmist. Project Pluto was a doomsday device,
made to be in the air for a LONG time before target identification, all the while flying low
and spreading deadly radiation in its path. Have a hundred of those circling the earth for
a few days, and you see what I mean.
You really think we made the world's first nuclear ramjet and "shelved" it?
Theres probably hundreds of these things in secret operational bunkers since the 1970's.
Sounds paranoid, but it isn't. Its just how we do things since OP Paperclip.