They only have to make it to Seoul.
I was stationed in Korea for a short while. One of the first orders of business was a briefing on the capabilities of each side.
Basically, each side has around 10 gazillion rockets pointed at each other, and if anything happens, a 60 mile wide strip at the DMZ get turned to dust.
For this reason, I’ve always thought it would not only be more provocative on an international stage, but would also be much safer for Kim jun Yaba Daba to launch a missile at Japan. For some reason, I believe that would ignite a response in the form of strongly worded letters, while a hit on Seoul initiates MAD on the peninsula.
As for the here and now, it seems the Chicom head Fred had such a good time meeting Trump, he may have green lighted a strike on the Nork nuke launching sites...and I would not at all be surprised if that happened soon.