gordan chang is the author of nuclear showdown. he joins us live from new york.nk you for being with us. >> thank you. >> in your estimation how long will it take for north korea to have a nuclear missile capable of hitting the u.s.? >> four years, january, 2011. robert gates said north korea within five years would be able to hit the united states with a missile. so we are now one year closer to that. of course, the north korea answer have a nuclear are weapon. by four years they will shrink it, make it into a miss and hit any city with pinpoint accuracy. by then we will not have any reliable defense against it. >> you mentioned the two things that north korea needs to perfect for this to happen. they have to perfect the nuke itself and the missile to carry t they are expecting to lawn were a missile test in a couple weeks. you expect that to be followed by other tests. >> in two years they conducted miss i am tests and within months of those tests they detonate add nuclear twice. you have to remember they sell both miss also and nukes. i mean we wouldn't buy a