commanded u.s. and allies forces say the u.s. should be ready strike north korean missiles on their path before they are launched if there's an imminent threat. >> the way you deter north korea is have the capability and the demonstrated willingness and the demonstrated planning and exercises to be able to respond strongly enough that north korea clearly understands that if they do that provocation they will be hurt more than we will be. >> reporter: general sharp says if u.s. forces hit kim jong-un's missiles first, he could retaliate and possibly on the 28,000 u.s. troops in south korea. u.s. forces might need to preempt that hitting conventional forces at the same time they strike missile facilities. dangerous proposition. >> certainly is.