[hddu]

How many foreign controlled nuclear weapons are currently on us soil?

Why spend billions developing rockets or stealth bombers when you can just load one up on a civilian boat, land on your enemies shore, and truck it to a safehouse in your target city. Let is sit there until you need to detonate it.

[evgen]

Given the amount of attention that has been paid to just this sort of scenario for more than two decades (along with prodigious spending on detection capability at ports) I would bet large sums that the answer to that is 0 or possibly 1. The danger of what you suggest is in getting caught, and the terribly unpleasant consequences of same; if I were in charge when some country tried that my first question would be if we knew where every family member of the leadership of that country slept...

[Nathanael_M]

Is this just a hypothetical or is there evidence of this taking place?

[TheOtherHobbes]

Considering the low cost and high potential reward it's a reasonable bet that all sides are either doing this or working on it.

And considering how easy it is to bypass ports while smuggling drugs, the idea that port monitoring will prevent it is unconvincing.

For obvious reasons, no side will announce its efforts publicly. Nor will any side announce discovery of other efforts until a hot war starts to seem like a good idea.