That also isn't enough without having a delivery vehicle that is reliable enough to give them a pause. And considering the distance a hypothetical missile would have to cross, it is a borderline impossible task. The reason they have so many bases around the world and so many fleets in the oceans is to protect the US mainland, not Europe or Japan or whatever. With all those bases and thousands of satellites they have, we would need to launch perhaps more than a 100 missiles, some real some decoys, so that maybe 1 or whatever might hit a target. But even that is not enough because then you are against a country with thousands of nukes, so, first one to draw doesn't get away scot-free against either.
I'm oversimplifying here but my point is simply having nukes is not enough to be a deterrent if US really wants to attack you. And when it comes to yanks, there is always something you haven't seen before waiting in the wings. We are talking about a country that spends more on their military in 1 year than we do in 20. More like 30 now actually.
So,
@Sanchez is right. We don't want to fight against them and if they really do, neither nukes nor air defence would be enough to stop them. And the only proven way to end it is bogging them down in a guerilla war that lasts for years until the cost exceeds the profit for them.