They have no "conventional" means to deliver them Dave. They could just ship them to an American port rather than put them on a missile. Any nation could do that.
Indeed, and most nations could get a walker through with a suitcase device. Neither situation would be strategically effective. Both situations would enrage the target and show the world (and you) that yes, they have far more of these things than you do and yes, they're willing to use them if provoked sufficiently.
Nobody wins in this case. Or rather, America loses less badly. This is not a victory for the other side, as after the dust settles, there would be no other side.
Strategically sound deployment would require enough nukes hitting enough targets to at least alter the target's foreign policy, if not actually destroy the target altogether. As we can see, this would require a lot of nukes, a lot of delivery systems, and at least a fair degree of accuracy. Bear in mind that the US's nuclear weapons program was developed with redundancy and second strike capability in mind; even if you somehow manage to knock off all the primary targets in one quick surprise salvo, there is a secondary system of retribution (and a command and control system to direct it) in place. There is no free lunch. Launch, and you will be launched upon. Even if you have completely destroyed America as a country, the retaliatory salvo will come and will be sufficient to ruin one's day. Unless the initiating country is the Soviet Union prior to the end of the Cold War, what's coming back will far outweigh what went out; even in that case, the outcome would be in doubt.
This is probably why the Cold War never went hot. NATO's policy was to deploy weapons of mass destruction in case of serious losses in a conventional war with the Warsaw Pact. The Warsaw Pact's policy was probably the same. Winning is meaningless if there's nothing left to win, and no one to claim the spoils.
How badly do you want to win this, and are you prepared to lose everything (including the ability to enjoy a perceived victory) to achieve it? This is the question that a nuclear nation looking for trouble must ask itself. This is not firing shots over a border or shooting a missile at a ship. This is nuclear war. All bets are off and the policy is not a secret; use nukes, and suffer nukes. If the other side has more of them than you this is not a winning equation. The rest of the world will suffer but be selfish for a moment: what about
me? What will happen to
my home if nuclear weapons are deployed?
The answer is that there will be no
you, and your home will cease to exist. This axiom guided the Cold War to its eventual death and will likely continue to guide future standoffs to a non-nuclear (if not non-violent) resolution.
The fly in the ointment is an entity, or entities, that posess a nuclear capability but aren't tied to a particular nation. Without accountability to a population and a location the system falls apart. Thus, again I'm not worried about nuclear nations; I'm worried about nuclear individuals, and how those individuals might attain said means.
When asked what would happen if Africa had nukes, I would respond with, "What if Israel had nukes? Or Pakistan? Or India? Or North Korea?"
No
nation has a desire to open this can of worms. Leaders may speak rhetoric but there is no requirement that they actually believe it. (And if they do, they'll likely not be leaders for very long.) It's a big saber to rattle but there are folks with bigger sabers.
We know that the UN doesn't work in this case. What else will? Sanctions that won't be supported? Military action? Who will this burden rest on? If they accept the burden, how long will it be before the rest of the have-nots decide that they've indeed had enough and do something about it? Enforcing such a thing is not only hypocritical, it's impossible.
Assuming that we ever find a way to enforce a global nuclear policy, how do we decide who gets nuclear technology and who doesn't? What if they rate power plants but can't have weapons? Who determines the difference between a purpose-built breeder reactor and one made to produce power that happens to have some plutonium left over? Who will enforce the decisions of this organization? What gives
anyone the right to pick the have's and the have-not's, and what qualifies them for this? (Be very careful how you answer this, if you choose to answer it at all.)
For a group of individuals that largely support the right to keep and bear arms, we seem remarkably selective about what arms people can keep and bear and who those people are.