States such as Germany and Italy who sit under the American nuclear umbrella seem reliant on NATO Article 5. Article 5, though, does not require the US to commit suicide on behalf of a militarily violated Member State. I’m sure that average Joe (or Jolene) American (who pays for that umbrella) would prefer some diplomatic compromise that fell short of swapping big bombs and didn’t materially affect the US; even if the aggrieved Member State was required to make massive concessions. I believe that it’s called Realpolitik.
The question is, does the World’s 6th (or is it 8th now?) largest economy, with many interests South of the NATO Region, want to risk being forced to those possible massive concessions?
Regarding the UN Security Council, the UK Independent (standing by for the predictable contradictions) Strategic Nuclear Deterrent is a good bargaining "chip" to retain our place there. Why have that place? Well, it’s probably better to have a say with power of veto than to not. Does it give us an obligation to help to "police" the World? Probably yes; but rather like the Empire, if we didn’t somebody else would and possibly not to our liking and standards.
Cruise missiles? Current technology, even that available to some minor States, probably puts us back to the ‘40s argument of whether it’s easier to counter a V1 or a V2.
Offered for what it’s worth.