I’m not sure what the joke is.

Sweden had an atomic bomb program which was dropped in the 1970s after assurances from the US to extend its “nuclear umbrella” to protect Sweden.

So if the USSR were to attack Sweden then what would the USA do exactly?

Do you mean Russia or USSR? It is unclear if you are asking about a hypothetical event in the past or a hypothetical event in the future after ratification of Sweden’s NATO membership.

I don’t know. Most of it is still classified, but whatever it was, it was enough to assure Swedish governments of the time. (70s - early 90s)

Interesting that Sweden sees modern Russia as a bigger threat than the USSR. Whatever there was before is not enough now and they want a full NATO membership instead.

Whatever there was before, was dismantled late eighties or early nineties, it’s hard to tell for sure.

One big reason Sweden jumped into NATO now is that the Swedish military is, not exactly a shadow of its former self, but very small.

If Sweden would have had an equivalent of the military power it had in say, 1991, I doubt a NATO application would have been made, or at least not as hastily.