Experts are now in quiet agreement that North Korea has miniaturised nuclear bombs enough to put them on medium-range missiles. That means that they can not reach the United States from their home land, but Japan and South Korea are easily within range. About that whole 'can not reach the USA yet', that will no longer be true soon enough. A few more "satellite" launches (Berman Post: North Korea Fires Missile, Berman Post: North Korea Releases Rocket Launch Video) and we will find our selves wanting a missile shield more than ever (Berman Post: Why we Need a Missile Shield).
More at http://www.timesonline.co.uk/tol/news/world/asia/article6155956.ece.