Before getting hot and bothered about what the Norks are doing, gotta determine first if it is threat or theatre. Our intel folks know the fuel NK uses is highly corrosive and not likely to spend a lot of time in the open before causing trouble. So reality intervenes here and demonstrates what appears to be is not what is.
Second, you can pretty much set your watch by Kim's tantrums. Shift the spotlight to the world's other nuclear nut-case and begin counting.
Third, Bush is no fool. He sees an opening when it shows. Democrats in congress have greatly reduced funding for ballistic missile defense (how they do that when the other party controls all levers of power in DC is another thread). Bush's opening is to sponsor a little theatre of his own rhetoric and the rhetoric of his spear carriers.
No threat, just good theatre. Ultimately, if Bush and Co. were really concerned about the missiles he could order a B2 decapitation strike interrupting Kim's plans and dinging his pretty playtoys. That, after all, is what the B2 was designed to do.