So first off, I don't like the headline. All US subs are nuclear, but this feels like burying the story: parking an SSBN at South Korea is a very specific message. It carries 20 Trident II missiles, each capable of carry 8 475kt warheads (but likely only armed with 4 due to treaty limitations).
38 Megatons of independently targetable nuclear destruction.
That said, the story also talks about how this will drive KJU from the table - as if he was ever there in the first place. Given the state of their current activities, I don't think reminding him that he's fucking around with a country that worked out nuclear delivery via ICBM half a century ago is overly aggressive.
IMO, at some point, someone (and I'm not saying the US necessarily) is going to have to go in and depose the regime and integrate the population into modern society. North Korea is a bigger threat to world stability than Russia, and today that's really saying something.