According to Paul Williams in his book Osama's revenge . the soviets planted possibly hundreds of suitcase nukes in the states during the coldwar. they just have to be assembled.
But are they still viable, even if this were true? Somehow, I doubt it...
Uh-oh...
The KGB routinely lost track of their caches in America. Ironically, the cause was capitalism and its process of creative destruction. Basically, the Russians would bury the stuff on the outskirts of the town they were interested in. A few years later, they'd look for the pine tree next to the pond, and all they'd see would be a strip mall and a couple fast-food joints.
Wonder how Osama's gonna find the stuff.