It is quite amazing how everyone is "answering" OP's question with the starting point being an assumption that North Korea is being provocative, prima facie. The lack of self-awareness is very striking. Rather interesting is this comment:
If you claim "I don't want to provoke anything," but engage in behavior, with belligerence, that escalates tensions and is more likely to provoke a confrontation than other behaviors, then the claim of "don't want to provoke anything" isn't really proven
The problem is that, if this rule is applied to the United States, apparently both sides are being provocative. After all, the United States is engaging in behavior, with belligerence, that escalates tensions and is more likely to provoke a confrontation, by sending two nuclear submarines with first-strike capability to the region, by performing massive military exercises just off of the shore, and by including in those exercises "decapitation strikes" specifically intended to kill Kim Jong Un. If Russia parked a nuclear fleet off of Delaware and practiced ways to kill Trump, how would we feel?
So maybe the question is "Why is North Korea described as provocative and the United States is not?"
Similarly striking is the absolute lack of knowledge about North Korea's stated foreign policy goals. I asked about this weeks ago and not a single user can come up with an answer. People are way too willing to eat up the highly filtered and biased information that is fed to them, as long as it is consistent with their nationalistic worldview. It doesn't even cross their minds that North Korea may be developing nuclear capability for defensive purposes, even though it is quite obvious that using them as an offensive option would result in their complete annihilation. The easier explanation for them to digest is that Kim Jong Un is simply crazy.
So, to answer the question, the apparent cause for this unequal treatment is that the media have a nationalistic or cultural bias in favor of their home country or in favor of the West of which they are part. An essential aspect of this is the notion of American Exceptionalism, whereby the United States can literally do no wrong, and can apply a different standard to other nations. Also part and parcel of this is the famous description of North Korea as the member of the Axis of Evil by Bush 43. And finally there is the intergenerational racism toward Asians found in the United States, due to bad blood from Pearl Harbor, Vietnam, and of course the Korean war in which America participated but never concluded.
And the effect of this bias is readily apparent in the answers provided on this post-- many, many Americans are completely unable to think-- for even a moment of imagination-- of North Korea in any way other than the one that has been pushed upon them by the media.