[Oatka]

In my world, I’d launch a missile with a non-nuclear warhead (HE) and fire it so it would land at the NK’s launch site about 10 seconds before their liftoff, then claim that the NK’s had an “explosive malfunction” at their launch - and offer condolences to the survivors.

A couple of such “malfunctions” ought to get the point across.

[Greysard]

I’d launch a missile with a non-nuclear warhead (HE) and fire it so it would land at the NK’s launch site about 10 seconds before their liftoff, then claim that the NK’s had an “explosive malfunction” at their launch - and offer condolences to the survivors.

It's not possible. According to Wikipedia, the USA doesn't have short range ballistic missiles. It used to have a few, but they are all discontinued. Perhaps there are some air-to-ground weapons, but I haven't checked.

You will have to buy 9K720 Iskander from Russia. It has the necessary range, and it can carry a variety of payloads. The speed would be 4,600 mph, so the payload can be delivered from the standoff range in under a minute. This will give you enough reaction time, once you realize that the launch sequence is initiated.