Either you accept North Korea should be allowed to have nuclear ICBMs, or you accept a red line has to be drawn and credible threats must be made
I've heard no one suggest that North Korea should be allowed to have nuclear. ICBMs.
But now that they may have them, threatening preemptive strikes is unlikely to make them give them up.
I believe that this new threat should be met by extremely severe sanctions, beyond anything that has been done up till now. Only if this fails to bring Kim Jong Un to the negotiating table should more extreme measures be employed.