The U.K. and France both have SSBNs. Russia did, and are at least building more, but I'm not sure if their SSBN fleet continued operating after the Cold War end

The U.K. and France both have SSBNs. Russia did, and are at least building more, but I'm not sure if their SSBN fleet continued operating after the Cold War ended. China is developing an SSBN fleet if they haven't already (and they do have other nukes). I think ICBM capability is the big question. Russia undoubtedly has it, and it's fair to say China probably does to. I'm not sure if the U.K. or France ever bothered to develop ballistic missiles to mate with their warheads but France at least could rather easily do it with their existing spacelift infrastructure.