Let's get the obvious out of the way first: of course, if it comes to a first strike by North Korea, then I'd fully expect the US to defend itself by any appropriate and necessary means. Not even up for debate, really.
It bothers me though that Trump seems to have essentially jumped to the last desperate measure of a Nuclear (counter)strike almost as a first resort. And no -- there doesn't seem to have been much advice of that sort from US military leaders, who would presumably have pointed out that the point of Nuclear weapons is *not* to use them, and anyway the US isn't necessarily ready yet for something so drastic (apparently, it could take several weeks to prepare properly, which is probably not too surprisingly really). The "fire and fury" line was made up by Trump on the spot -- not the first time he's done that, either against or without the advice of top generals (the "Transgender ban" was another one that turns out to have been dreamed up without the knowledge of the Pentagon).
It's dangerous to escalate the rhetoric quite so quickly; North Korea doesn't seem to be cowed by the talk and if anything has just escalated in kind. We can't know that they wouldn't just have carried on ramping up the tension anyway -- I suspect they probably would have -- but still Trump's jumped in all guns blazing and that hasn't really helped either.
I'm reminded a little of Obama's "line in the sand" moment. The problem is that he went ahead and announced said line (with respect to Syria, at least) before checking that everyone else who needed to agree with him on that actually did so. Turns out they didn't, he had to back down, and it looked foolish (because it was foolish). Will Trump's "fire and fury" be the same? Or is he going to carry through on his effective threat to launch nuclear weapons? To be honest, I am not sure which is the scarier option.
If it comes to military action, then, as I say, I would fully support whatever is needed to combat the threat from North Korea. What I am saying -- and what I think a few others are saying -- is that it may not need to come to that, and I hope that Trump gives other options due consideration before going too far down a road that could lead to a Nuclear War.