Kim Jong Un talks big but the success of launching a missile attack to Hawaii or mainland US is slim to none.  Takes a lot of development time & testing to fire missile that will hit its target 1000's miles away.  The threat is S Korea, such as Seoul & possibly Guam, but bet the US has already deployed the latest & greatest anti missile technology to the Guam military bases.  It is NOT helpful for Trump to match Jong Un's threats & only causes destabilization of the entire continent & the world.  Roosevelt was right for the US to "speak softly but carry a big stick" as garans the US has nuclear ballistic missile subs near Japan that can lay waste N Korean many times over (doubt neutron bombs but that would be better & allow the land of N Korea to be eventually reclaimed by S Korea. China would want a piece as well) .  Trump should not say anything for the US to have clean hands & plausible deniability to help S Korea wipe out N Korea in the event KimJong Un actually launches an attack.