Sheer idiocy? Look who we're talking about here. When have you ever known the North Korean regime to practice sanity, as a rule?
Granted, I'm just a tad bit biased, because I had a couple Nork MiGs scrambled against me in the Sea of Japan (international waters) back in 2003...
Their 2006 underground nuke test was considered a "fizzle" by those of us in the community - but it showed the world in no uncertain terms that they were willing to reprocess spent fuel rods from the Yongbyon reactor to extract the Pu239, and subsequently assemble a device that was really close to obtaining full yield from the fuel used. BTW, they didn't even wait the normal amount of time for the spent fuel rods to cool off, they were insanely radioactive when reprocessing began. Sanity, indeed - zorch a bunch of reprocessing facility workers to get that weapons-grade stuff for the greater good of North Korea.
The same unbelievable, nothing-to-lose mindset goes into their Taepo-Dong multistage missiles. They've demonstrated that they're more than willing to try, and launch one over somebody else's sovereign territory, damn the consequences. It got Japan's attention, most definitely.
In layman's terms:
Look at me! I have a delivery system, and a weapon! They may not be capable of integration this week, but by Great Leader, watch out!
That's why Uncle Sam spends a lot of time and effort with respect to posturing by North Korea, be it by our continuous WC/RC-135 sorties, or a posse of Aegis cruisers waiting to splash the damned things upon launch. If/when the ABL program goes operational, that will be added to the fray, as per its intended design. If China and neighboring countries cannot keep the Norks hemmed in, then we're not going to sit still and watch them launch crap that can hit Alaska and the CONUS. So we're going to nip it in the bud, right there, parked off their east coast. (Rightfully so, I might add)